1. Introduction
This document is the specification of the Java API for JavaBean validation in Java EE and Java SE. The technical objective of this work is to provide an object level constraint declaration and validation facility for the Java application developer, as well as a constraint metadata repository and query API.
It also offers method and constructor validation facilities to ensure constraints on their parameters and return values.
1.1. Expert group
This work has been conducted as part of JSR 380 and formerly JSRs 349 and 303 under the Java Community Process Program. This specification is the result of the collaborative work of the members of the JSR 380 Expert Group and the community at large.
The following persons have actively contributed to Bean Validation 2.0 as members of the JSR 380 expert group and the community at large in alphabetical order:
-
Matt Benson
-
Emmanuel Bernard (Red Hat, Inc.)
-
Linda DeMichiel (Oracle)
-
Hendrik Ebbers (Canoo AG)
-
Hardy Ferentschik (Red Hat, Inc.)
-
Christian Kaltepoth (ingenit GmbH & Co. KG)
-
Werner Keil
-
Marco Molteni (Genidea Sagl)
-
Gunnar Morling (Red Hat, Inc.) - Specification Lead
-
Michael Nascimento Santos
-
Otavio Santana
-
Guillaume Smet (Red Hat, Inc.)
-
Tsuyoshi Yoshitomi (Fujitsu Limited)
The following persons have actively contributed to Bean Validation 1.1 as members of the JSR 349 expert group and the community at large in alphabetical order:
-
Matt Benson
-
Paul Benedict
-
Emmanuel Bernard (Red Hat, Inc.) - Specification Lead
-
Edward Burns (Oracle)
-
Peter Davis
-
Linda DeMichiel (Oracle)
-
Hardy Ferentschik (Red Hat, Inc.)
-
Antonio Goncalves
-
Cemalettin KoƧ
-
Rich Midwinter
-
Gunnar Morling (individual then Red Hat, Inc.)
-
Pete Muir (Red Hat, Inc.)
-
Michael Nascimento Santos
-
Gerhard Petracek
-
Kevin Pollet (SERLI)
-
Jagadish Prasath Ramu (Oracle)
-
Bill Shannon (Oracle)
-
Sebastian Thomschke
Former expert group members of JSR-303 in alphabetical order are:
-
Geert Bevin
-
Emmanuel Bernard (Red Hat, Inc.) - Specification Lead
-
Uri Boness
-
Erik Brakkee (Ericsson AB)
-
Ed Burns (Sun Microsystems, Inc.)
-
Jason Carreira
-
Robert Clevenger (Oracle - retired)
-
Linda DeMichiel (Sun Microsystems, Inc.)
-
Tim Fennel
-
Bharath Ganesh (Pramati Technologies)
-
Romain Guy (Google Inc.)
-
Robert Harrop
-
Jacob J. Hookom
-
Bob Lee (Google Inc.)
-
Craig R. McClanahan (Sun Microsystems, Inc.)
-
Niall K. Pemberton
-
Steve Peterson
-
Dhanji R. Prasanna (Google Inc., formerly individual)
-
Gerhard Petracek
-
Matt Raible
-
Michael Nascimento Santos
-
Sebastian Thomschke
-
Jon Wetherbee (Oracle)
1.2. Specification goals
Validating data is a common task that occurs throughout an application, from the presentation layer to the persistence layer. Often the same validation logic is implemented in each layer, proving to be time consuming and error-prone. To avoid duplication of these validations in each layer, developers often bundle validation logic directly into the domain model, cluttering domain classes with validation code that is, in fact, metadata about the class itself.
This JSR defines a metadata model and API for JavaBean validation. The default metadata source is annotations, with the ability to override and extend the metadata through the use of XML validation descriptors.
The validation API developed by this JSR is not intended for use in any one tier or programming model. It is specifically not tied to either the web tier or the persistence tier, and is available for both server-side application programming, as well as rich client Swing application developers. This API is seen as a general extension to the JavaBeans object model, and as such is expected to be used as a core component in other specifications. Ease of use and flexibility have influenced the design of this specification.
As of version 1.1, Bean Validation constraints can also be applied to the parameters and return values of methods of arbitrary Java types. Thus the Bean Validation API can be used to describe and validate the contract (comprising pre- and postconditions) applying to a given method ("Programming by Contract", PbC). Note that it is not the goal of this specification to develop a fully-fledged PbC solution but rather an easy-to-use facility satisfying the most common needs related to applying constraints to method parameters and return values, based on the proven concepts of the Bean Validation API.
1.3. Required Java version
The specification uses Java 8 language features. There is no requirement that implementations be compatible with Java language versions prior to 8.
1.4. How this document is organized
This document describes each aspect of the Bean Validation specification in a separate chapter. One should remember that the specification is a consistent whole.
Constraint definition describes how constraints are defined.
Value extractor definition describes how extractors for the values of container types are defined.
Constraint declaration and validation process describes how a JavaBean class is decorated with annotations to describe constraints.
Validation APIs describes how to programmatically validate a JavaBean.
Constraint metadata request APIs describes how the metadata query API works.
Built-in Constraint definitions list all the built-in constraints.
XML deployment descriptor describes the XML deployment descriptors for the configuration and the mapping.
Exception model describes the exception model and hierarchy used by Bean Validation.
Integration describes the different integration points of Bean Validation with other technologies. In some cases one has to refer to the respective specifications for the up-to-date integration rules.
In Terminology, key concepts are summarized. Some reviewers have found that reading the terminology section first helps to better understand the specification.
The changelog can be found at Changelog.
1.5. How to comment
The expert group is eager to receive feedback from readers. Feel free to contact us. You can get all the details at http://beanvalidation.org/contribute/.
2. What’s new
2.1. What’s new in 2.0
The main contribution of Bean Validation 2.0 is leveraging the new language features and API additions of Java 8 for the purposes of validation. Java 8 or later is required to use Bean Validation 2.0.
The changes include:
-
Support for validating container elements by annotating type arguments of parameterized types, e.g.
List<@Positive Integer> positiveNumbers
(see Container element constraints); this also includes:-
More flexible cascaded validation of collection types; e.g. values and keys of maps can be validated now:
Map<@Valid CustomerType, @Valid Customer> customersByType
-
Support for
java.util.Optional
-
Support for the property types declared by JavaFX
-
Support for custom container types by plugging in additional value extractors (see Value extractor definition)
-
-
Support for the new date/time data types for
@Past
and@Future
(see Built-in Constraint definitions); fine-grained control over the current time and time zone used for validation (see Implementation of temporal constraint validators) -
New built-in constraints:
@Email
,@NotEmpty
,@NotBlank
,@Positive
,@PositiveOrZero
,@Negative
,@NegativeOrZero
,@PastOrPresent
and@FutureOrPresent
(see Built-in Constraint definitions) -
All built-in constraints are marked as repeatable now
-
Parameter names are retrieved using reflection (see Naming parameters)
-
ConstraintValidator#initialize()
is a default method (see Constraint validation implementation) -
The namespace for Bean Validation XML descriptors has been changed to
http://xmlns.jcp.org/xml/ns/validation/configuration
forMETA-INF/validation.xml
andhttp://xmlns.jcp.org/xml/ns/validation/mapping
for constraint mapping files (see XML configuration: META-INF/validation.xml)
2.2. What’s new in 1.1
Bean Validation 1.1 improves and builds upon Bean Validation 1.0. The expert group and the community have been working on a few specific areas.
2.2.1. Openness
All of Bean Validation 1.1 work has been done in the open and in an open source way. Source code for the API, reference implementation, test compatibility kit as well as the specification and the website sources are available in the open. All discussions are done in the open in the publicly available development mailing list. Road map and proposals are also published on the website.
You can find all the details (mailing lists, source repositories etc.) at http://beanvalidation.org.
2.2.2. Dependency injection
Bean Validation uses a few components MessageInterpolator
, TraversableResolver
, ParameterNameProvider
, ConstraintValidatorFactory
and ConstraintValidator
. Bean Validation 1.1 standardizes how these objects are managed by a container and how these objects can benefit from container services. In particular, CDI support within Java EE is being defined.
2.2.3. Method validation
Bean Validation 1.1 allows to put constraints to the parameters and return values of arbitrary methods and constructors. That way the Bean Validation API can be used to describe and validate the contract applying to a given method or constructor, that is:
-
the preconditions that must be met by the caller before the method or constructor may be invoked and
-
the postconditions that are guaranteed to the caller after a method or constructor invocation returns.
This enables a programming style known as "Programming by Contract" (PbC). Compared to traditional means of checking the sanity of argument and return values this approach has several advantages:
-
These checks are expressed declaratively and don’t have to be performed manually, which results in less code to write, read and maintain.
-
The pre- and postconditions applying for a method or constructor don’t have to be expressed again in the documentation, since any of its annotations will automatically be included in the generated JavaDoc. This reduces redundancies, thus avoiding efforts and inconsistencies between implementation and documentation.
2.2.4. Integration with Context and Dependency Injection
The integration points with Context and Dependency Injection (CDI) have been increased and reworked. This opens up for a more natural and standard integration both in Java EE and Java SE and encompass dependency injection, component lifecycle management and interception for method validation.
2.2.5. Group conversion
The specification offers a way to alter the targeted group when validation cascading is happening. This feature is particularly useful to reuse a given object (graph) and to avoid leaking groups between various object subgraphs. It also makes for more readable constraints.
2.2.6. Message interpolation via the unified expression language
Constraint violation messages can now use EL expressions for a much more flexible rendering and string formatting. In particular a formatter object is injected in the EL context to convert numbers, dates etc. into the locale specific string representation. Likewise, the validated value is also available in the EL context.
2.2.7. Others
Many more minor changes have been done. Check out the change log for more details at Changelog.
3. Constraint definition
Constraints are defined by the combination of a constraint annotation and a list of constraint validation implementations. The constraint annotation is applied on types, fields, methods, constructors, parameters, container elements or other constraint annotations in case of composition.
Unless stated otherwise the default package name for the Bean Validation APIs is javax.validation
.
3.1. Constraint annotation
A constraint on a JavaBean is expressed through one or more annotations. An annotation is considered a constraint definition if its retention policy contains RUNTIME
and if the annotation itself is annotated with javax.validation.Constraint
.
@Constraint
annotation/**
* Marks an annotation as being a Bean Validation constraint.
* <p>
* A given constraint annotation must be annotated by a {@code @Constraint}
* annotation which refers to its list of constraint validation implementations.
* <p>
* Each constraint annotation must host the following attributes:
* <ul>
* <li>{@code String message() default [...];} which should default to an error
* message key made of the fully-qualified class name of the constraint followed by
* {@code .message}. For example {@code "{com.acme.constraints.NotSafe.message}"}</li>
* <li>{@code Class<?>[] groups() default {};} for user to customize the targeted
* groups</li>
* <li>{@code Class<? extends Payload>[] payload() default {};} for
* extensibility purposes</li>
* </ul>
* <p>
* When building a constraint that is both generic and cross-parameter, the constraint
* annotation must host the {@code validationAppliesTo()} property.
* A constraint is generic if it targets the annotated element and is cross-parameter if
* it targets the array of parameters of a method or constructor.
* <pre>
* ConstraintTarget validationAppliesTo() default ConstraintTarget.IMPLICIT;
* </pre>
* This property allows the constraint user to choose whether the constraint
* targets the return type of the executable or its array of parameters.
*
* A constraint is both generic and cross-parameter if
* <ul>
* <li>two kinds of {@code ConstraintValidator}s are attached to the
* constraint, one targeting {@link ValidationTarget#ANNOTATED_ELEMENT}
* and one targeting {@link ValidationTarget#PARAMETERS},</li>
* <li>or if a {@code ConstraintValidator} targets both
* {@code ANNOTATED_ELEMENT} and {@code PARAMETERS}.</li>
* </ul>
*
* Such dual constraints are rare. See {@link SupportedValidationTarget} for more info.
* <p>
* Here is an example of constraint definition:
* <pre>
* @Documented
* @Constraint(validatedBy = OrderNumberValidator.class)
* @Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
* @Retention(RUNTIME)
* public @interface OrderNumber {
* String message() default "{com.acme.constraint.OrderNumber.message}";
* Class<?>[] groups() default {};
* Class<? extends Payload>[] payload() default {};
* }
* </pre>
*
* @author Emmanuel Bernard
* @author Gavin King
* @author Hardy Ferentschik
*/
@Documented
@Target({ ANNOTATION_TYPE })
@Retention(RUNTIME)
public @interface Constraint {
/**
* {@link ConstraintValidator} classes implementing the constraint. The given classes
* must reference distinct target types for a given {@link ValidationTarget}. If two
* {@code ConstraintValidator}s refer to the same type, an exception will occur.
* <p>
* At most one {@code ConstraintValidator} targeting the array of parameters of
* methods or constructors (aka cross-parameter) is accepted. If two or more
* are present, an exception will occur.
*
* @return array of {@code ConstraintValidator} classes implementing the constraint
*/
Class<? extends ConstraintValidator<?, ?>>[] validatedBy();
}
A constraint is said to be generic if it has at least one constraint validator targeting the element annotated i.e. targeting the (returned) element annotated by the constraint (a bean, a field, a getter, a method/constructor return value or a method/constructor parameter). A constraint is said to be cross-parameter if it has one constraint validator targeting the array of parameters of a method or constructor (to validate the consistency of several method/constructor parameters). A Bean Validation constraint is most of the time either a generic constraint or a cross-parameter constraint. In rare situations, a constraint can be both.
Generic constraint annotations can target any of the following ElementType
s:
-
FIELD
for constrained attributes -
METHOD
for constrained getters and constrained method return values -
CONSTRUCTOR
for constrained constructor return values -
PARAMETER
for constrained method and constructor parameters -
TYPE
for constrained beans -
ANNOTATION_TYPE
for constraints composing other constraints -
TYPE_USE
for container element constraints
Cross-parameter constraint annotations can target any of the following ElementType
s:
-
METHOD
-
CONSTRUCTOR
-
ANNOTATION_TYPE
for cross-parameter constraints composing other cross-parameter constraints
A constraint annotation that is both can target the union of the generic and cross-parameter constraint annotations targets.
While other ElementType
s are not forbidden, the provider does not have to recognize and process constraints placed on such types.
Since a given constraint definition applies to one or more specific Java types, the JavaDoc for the constraint annotation should clearly state which types are supported. Applying a constraint annotation to an incompatible type will raise an UnexpectedTypeException
. Care should be taken on defining the list of ConstraintValidator
s. The type resolution algorithm (see ConstraintValidator resolution algorithm) could lead to exceptions if the ConstraintValidator
list leads to ambiguities.
At most one ConstraintValidator
supporting cross-parameter validation must be present for a given constraint. A ConstraintDefinitionException
is raised otherwise. The JavaDoc should clearly state if the constraint is a generic and / or a cross-parameter constraint.
If a constraint definition is not valid, a ConstraintDefinitionException
is raised either at validation time or when the metadata is requested. Invalid constraint definitions causes are multiple but include missing or illegal message
or groups
elements (see Constraint definition properties).
Note
|
Bean Validation defines rules for applying constraint annotations in inheritance hierarchies, described in Inheritance (interface and superclass) and Method constraints in inheritance hierarchies. It is therefore not recommended to specify the meta annotation |
3.1.1. Constraint definition properties
A constraint definition may have attributes that are specified at the time the constraint is applied to a JavaBean. The properties are mapped as annotation elements. The annotation element names message
, groups
, validationAppliesTo
and payload
are considered reserved names; annotation elements starting with valid
are not allowed ; a constraint may use any other element name for its attributes.
3.1.1.1. message
Every constraint annotation must define a message
element of type String
.
String message() default "{com.acme.constraint.MyConstraint.message}";
The message
element value is used to create the error message. See Message interpolation for a detailed explanation. It is recommended to default message
values to resource bundle keys to enable internationalization. It is also recommended to use the following convention: the resource bundle key should be the fully qualified class name of the constraint annotation concatenated to .message
as shown in the previous program listing.
Built-in Bean Validation constraints follow this convention.
3.1.1.2. groups
Every constraint annotation must define a groups
element that specifies the processing groups with which the constraint declaration is associated. The type of the groups
parameter is Class<?>[]
.
Class<?>[] groups() default {};
The default value must be an empty array.
If no group is specified when declaring the constraint on an element, the Default
group is considered declared.
See groups for more information.
Groups are typically used to control the order in which constraints are evaluated, or to perform validation of the partial state of a JavaBean.
3.1.1.3. payload
Constraint annotations must define a payload
element that specifies the payload with which the constraint declaration is associated. The type of the payload
parameter is Payload[]
.
Class<? extends Payload>[] payload() default {};
The default value must be an empty array.
Each attachable payload extends Payload
.
Payload
interface/**
* Payload type that can be attached to a given
* constraint declaration.
* <p>
* Payloads are typically used to carry on metadata information
* consumed by a validation client.
* </p>
* With the exception of the {@link Unwrapping} payload types, the use of payloads is not
* considered portable.
*
* @author Emmanuel Bernard
* @author Gerhard Petracek
*/
public interface Payload {
}
Payloads are typically used by validation clients to associate some metadata information with a given constraint declaration.
Describing payloads as interface extensions as opposed to a string-based approach allows an easier and more type-safe approach.
Payloads are typically non-portable.
An exception are the Unwrapping.Skip
and Unwrapping.Unwrap
payload types which are defined by this specification (see Implicit unwrapping of containers).
One use case for payload shown in Use of payload to associate severity to a constraint is to associate a severity to a constraint. This severity can be exploited by a presentation framework to adjust how a constraint failure is displayed.
package com.acme.severity;
public class Severity {
public static class Info implements Payload {};
public static class Error implements Payload {};
}
public class Address {
@NotNull(message="would be nice if we had one", payload=Severity.Info.class)
public String getZipCode() { [...] }
@NotNull(message="the city is mandatory", payload=Severity.Error.class)
String getCity() { [...] }
}
The payload
information can be retrieved from error reports via the ConstraintDescriptor
either accessed through the ConstraintViolation
objects (see ConstraintViolation) or through the metadata API (see ConstraintDescriptor).
3.1.1.4. validationAppliesTo
validationAppliesTo
is used at constraint declaration time to clarify what the constraint targets (i.e. the annotated element, the method return value or the method parameters).
The element validationAppliesTo
must only be present for constraints that are both generic and cross-parameter, it is mandatory in this situation. A ConstraintDefinitionException
is raised if these rules are violated.
The type of the validationAppliesTo
parameter is ConstraintTarget
. The default value must be ConstraintTarget.IMPLICIT
.
ConstraintTarget validationAppliesTo() default ConstraintTarget.IMPLICIT;
/**
* Defines the constraint target.
*
* @author Emmanuel Bernard
* @since 1.1
*/
public enum ConstraintTarget {
/**
* Discover the type when no ambiguity is present
* <ul>
* <li>if neither on a method nor a constructor, it implies the annotated element
* (type, field etc),</li>
* <li>if on a method or constructor with no parameter, it implies
* {@code RETURN_VALUE},</li>
* <li>if on a method with no return value ({@code void}), it implies
* {@code PARAMETERS}.</li>
* </ul>
* Otherwise, {@code IMPLICIT} is not accepted and either {@code RETURN_VALUE} or
* {@code PARAMETERS} is required. This is the case for constructors with parameters
* and methods with parameters and return value.
*/
IMPLICIT,
/**
* Constraint applies to the return value of a method or a constructor.
*/
RETURN_VALUE,
/**
* Constraint applies to the parameters of a method or a constructor
*/
PARAMETERS
}
If a ConstraintTarget
is used in an illegal situation, a ConstraintDeclarationException
is raised either at validation time or when the metadata is requested. Examples of illegal situations are:
-
using
IMPLICIT
in a situation that cannot be inferred (see the JavaDoc for the detailed rules), -
using
PARAMETERS
on a constructor or method that has no parameter, -
using
RETURN_VALUE
on a method with no return value, -
using
PARAMETERS
orRETURN_VALUE
on a type - class or interface - or on a field.
Constraint users are encouraged to explicitly set the ConstraintTarget
target when using a constraint supporting both on a method or constructor as it improves readability.
3.1.1.5. Constraint specific parameter
The constraint annotation definitions may define additional elements to parameterize the constraint. For example, a constraint that validates the length of a string can use an annotation element named length
to specify the maximum length at the time the constraint is declared.
3.1.2. Examples
//assuming OrderNumberValidator is a generic constraint validator
package com.acme.constraint;
/**
* Mark a String as representing a well formed order number
*/
@Documented
@Constraint(validatedBy = OrderNumberValidator.class)
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
public @interface OrderNumber {
String message() default "{com.acme.constraint.OrderNumber.message}";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
}
Simple constraint definition marks a String
as a well-formed order number. The constraint validator is implemented by OrderNumberValidator
.
//assuming DateParametersConsistentValidator is a cross-parameter
//constraint validator
package com.acme.constraint;
/**
* Cross-parameter constraint ensuring that two date parameters of a method are in the
* correct order.
*/
@Documented
@Constraint(validatedBy = DateParametersConsistentValidator.class)
@Target({ METHOD, CONSTRUCTOR, ANNOTATION_TYPE })
@Retention(RUNTIME)
public @interface DateParametersConsistent {
String message() default "{com.acme.constraint.DateParametersConsistent.message}";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
}
Simple cross-parameter constraint definition shows a cross-parameter constraint which ensures that two date parameters of a method are in the correct order. The constraint validator is implemented by DateParametersConsistentValidator
.
//assuming ELAssertValidator is both a generic and cross-parameter
//constraint validator
package com.acme.constraint;
/**
* EL expression to be validated. This constraint accepts any type and can validate both the
* annotated type or apply restrictions across parameters.
*/
@Documented
@Constraint(validatedBy = ELAssertValidator.class)
@Target({ METHOD, FIELD, TYPE, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
public @interface ELAssert {
String message() default "{com.acme.constraint.ELAssert.message}";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
ConstraintTarget validationAppliesTo() default ConstraintTarget.IMPLICIT;
String expression();
}
@ELAssert(
message="Please check that your passwords match and try again.",
expression="param[1]==param[2]",
validationAppliesTo=ConstraintType.PARAMETERS
)
public User createUser(String email, String password, String repeatPassword) { [...] }
Constraint that is both generic and cross parameter shows a constraint that can be applied both on the annotated element and across parameters of a method or a constructor. Note in this case the presence of validationAppliesTo
.
package com.acme.constraint;
/**
* A frequency in Hz as audible to human ear. Adjustable to the age of the person. Accepts
* Numbers.
*/
@Documented
@Constraint(validatedBy = AudibleValidator.class)
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
public @interface Audible {
Age age() default Age.YOUNG;
String message() default "{com.acme.constraint.Audible.message}";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
public enum Age {
YOUNG,
WONDERING,
OLD
}
}
Constraint definition with default parameter ensures that a given frequency is within the scope of human ears. The constraint definition includes an optional parameter that may be specified when the constraint is applied.
package com.acme.constraint;
/**
* Defines the list of values accepted. Accepts int or Integer objects.
*/
@Documented
@Constraint(validatedBy = DiscreteListOfIntegerValidator.class)
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
public @interface Acceptable {
int[] value();
String message() default "{com.acme.constraint.Acceptable.message}";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
}
Constraint definition with mandatory parameter defines a list of acceptable values expressed as an array: the value
property must be specified when the constraint is applied.
3.2. Applying multiple constraints of the same type
It is often useful to declare the same constraint more than once to the same target, with different properties. A common example is the @Pattern
constraint, which validates that its target matches a specified regular expression. Other constraints have this requirement as well. The same constraint type can belong to different groups and have specific error messages depending on the targeted group.
To support this requirement, the Bean Validation provider treats regular annotations (annotations not annotated by @Constraint
) whose value
element has a return type of an array of constraint annotations in a special way. Each element in the value
array are processed by the Bean Validation implementation as regular constraint annotations. This means that each constraint specified in the value
element is applied to the target. The annotation must have retention RUNTIME
and can be applied on a type, field, property, executable parameter, executable return value, executable cross-parameter or another annotation. It is recommended to use the same set of targets as the initial constraint.
Note to constraint designers: each constraint annotation should be coupled with its corresponding multi-valued annotation. The specification recommends, though does not mandate, the definition of an inner annotation named List
.
Each constraint annotation type should be meta-annotated with java.lang.annotation.Repeatable
, referencing the corresponding List
annotation.
This marks the constraint annotation type as repeatable and lets users specify the constraint several times without explicitly using the List
annotation.
All built-in annotations follow this pattern.
/**
* Validate a zip code for a given country
* The only supported type is String
*/
@Documented
@Constraint(validatedBy = ZipCodeValidator.class)
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
public @interface ZipCode {
String countryCode();
String message() default "{com.acme.constraint.ZipCode.message}";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
/**
* Defines several @ZipCode annotations on the same element
* @see (@link ZipCode}
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
ZipCode[] value();
}
}
public class Address {
@ZipCode(countryCode = "fr", groups = Default.class, message = "zip code is not valid")
@ZipCode(
countryCode = "fr",
groups = SuperUser.class,
message = "zip code invalid. Requires overriding before saving."
)
private String zipCode;
}
In this example, both constraints apply to the zipCode
field but with different groups and with different error messages.
It is also possible to specify a constraint several times by explicitly using the @List
annotation
(though simply repeating the annotation is the preferred idiom as of Bean Validation 2.0 and Java 8):
@List
annotation (discouraged)public class Address {
@ZipCode.List( {
@ZipCode(countryCode="fr", groups=Default.class,
message = "zip code is not valid"),
@ZipCode(countryCode="fr", groups=SuperUser.class,
message = "zip code invalid. Requires overriding before saving.")
} )
private String zipCode;
}
Using two different multi-constraint annotations for the same underlying constraint type on the same target (i.e. class or property) is not considered portable and is discouraged.
3.3. Constraint composition
This specification allows you to compose constraints to create higher level constraints.
Constraint composition is useful in several ways:
-
Avoid duplication and facilitate reuse of more primitive constraints.
-
Expose primitive constraints as part of a composed constraint in the metadata API and enhance tool awareness.
Composition is done by annotating a constraint annotation with the composing constraint annotations.
@Pattern(regexp = "[0-9]*")
@Size(min = 5, max = 5)
@Constraint(validatedBy = FrenchZipCodeValidator.class)
@Documented
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
public @interface FrenchZipCode {
String message() default "Wrong zip code";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
FrenchZipCode[] value();
}
}
Annotating an element with @FrenchZipCode
(the composed annotation) is equivalent to annotating it with @Pattern(regexp="[0-9]*")
, @Size(min=5, max=5)
(the composing annotations) and @FrenchZipCode
. More formally, each constraint annotation hosted on a constraint annotation is applied to the target element and this is done recursively. Note that the main annotation and its constraint validation implementation is also applied. By default, each failing constraint generates an error report. Groups from the main constraint annotation are inherited by the composing annotations. Any groups
definition on a composing annotation is ignored. Payload from the main constraint annotation is inherited by the composing annotations. Any payload
definition on a composing annotation is ignored. The constraint target from the main constraint annotation is inherited by the composing annotations. Any validationAppliesTo
definition on a composing annotation is ignored.
The type upon which composed constraint is placed must be compatible with all constraints (composing and composed). A constraint designer should ensure that such a type exists and lists in the JavaDoc all the compatible types.
All composed and composing constraints must have a constraint type in common. In particular, it is not legal to mix a pure generic constraint and a pure cross-parameter constraint.
It is possible to ensure that composing annotations do not raise individual error reports. In this scenario, if one or more composing annotations are invalid, the main constraint is automatically considered invalid and the corresponding error report is generated. To mark a constraint as raising a single constraint error report if either the composed or one of the composing constraints fail, use the @ReportAsSingleViolation
annotation.
@FrenchZipCode
is raised and none other.@Pattern(regexp = "[0-9]*")
@Size(min = 5, max = 5)
@ReportAsSingleViolation
@Constraint(validatedBy = FrenchZipCodeValidator.class)
@Documented
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
public @interface FrenchZipCode {
String message() default "Wrong zip code";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
FrenchZipCode[] value();
}
}
The definition of @ReportAsSingleViolation
is as follows.
@ReportAsSingleViolation
annotation/**
* A constraint annotation hosting this annotation will return the
* composed annotation error report if any of the composing annotations fail.
* The error reports of each individual composing constraint are ignored.
* <p>
* Note: Evaluation of composed constraints stops on the first validation
* error in case the composing constraint is annotated with
* {@code @ReportAsSingleViolation}.
*
* @author Emmanuel Bernard
*/
@Target({ ANNOTATION_TYPE })
@Retention(RUNTIME)
@Documented
public @interface ReportAsSingleViolation {
}
More specifically, if a composed constraint is marked as @ReportAsSingleViolation
, the evaluation of the composing constraints stops at the first failing constraint and the error report corresponding to the composed constraint is generated and returned.
Composing annotations can define the value of message
and custom attributes (excluding groups
, payload
and validationAppliesTo
) but these are fixed in the composed constraint definition.
@FrenchZipCode
constraints have a @Size
restricted to 5.@Pattern(regexp = "[0-9]*")
@Size(min = 5, max = 5)
@Constraint(validatedBy = FrenchZipCodeValidator.class)
@Documented
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
public @interface FrenchZipCode {
String message() default "Wrong zip code";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
FrenchZipCode[] value();
}
}
It is possible to override attributes and messages defined on a composing annotation.
An attribute from the main annotation is used to override one or more attributes of the composing annotations.
Such an attribute is annotated with one or more @OverridesAttribute
annotations.
@Pattern(regexp = "[0-9]*")
@Size
@Constraint(validatedBy = FrenchZipCodeValidator.class)
@Documented
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
public @interface FrenchZipCode {
String message() default "Wrong zip code";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
@OverridesAttribute(constraint = Size.class, name = "min")
@OverridesAttribute(constraint = Size.class, name = "max")
int size() default 5;
@OverridesAttribute(constraint = Size.class, name = "message")
String sizeMessage() default "{com.acme.constraint.FrenchZipCode.zipCode.size}";
@OverridesAttribute(constraint = Pattern.class, name = "message")
String numberMessage() default "{com.acme.constraint.FrenchZipCode.number.size}";
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
FrenchZipCode[] value();
}
}
The value of the composed constraint attribute annotated with @OverridesAttribute
(@FrenchZipCode.sizeMessage
) is applied to the composing constraint attribute named after @OverridesAttribute.name
and hosted on the composing constraint of type @OverridesAttribute.constraint
(@Size.message
). Similarly, @FrenchZipCode.numberMessage
value is mapped to @Pattern.message
.
If left undefined, the default value for @OverridesAttribute.name
is the name of the composed constraint attribute hosting the @OverridesAttribute
annotation.
The types of the overridden and overriding attributes must be identical.
Note
|
A composing constraint can itself be a composed constraint. In this case, attribute values are overridden recursively according to the described rules. Note however, that a forwarding rule (as defined by |
Using Attributes from composing annotations can be overridden by attributes from the composed annotation,
@FrenchZipCode(size=9, sizeMessage="Zip code should be of size {max}")
is equivalent to
@FrenchZipCode
if @FrenchZipCode
is defined as
@Pattern(regexp = "[0-9]*")
@Size(min = 9, max = 9, message = "Zip code should be of size {max}")
@Constraint(validatedBy = FrenchZipCodeValidator.class)
@Documented
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
public @interface FrenchZipCode {
String message() default "Wrong zip code";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
FrenchZipCode[] value();
}
}
If a constraint is used more than once as a composing constraint, the multi value constraints model as described in Applying multiple constraints of the same type is used.
To select a specific composing constraint, OverridesAttribute.constraintIndex
is used.
If the composing constraints are directly given on the composed constraint (i.e. via the repeatable annotation feature), constraintIndex
refers to the left-to-right order of the constraints of this type in which they are given on the composed constraint.
If the composing constraints are specified using their corresponding List
annotation, constraintIndex
refers to the index within the value
array.
A composing constraint must not be given directly on the composed constraint and using the corresponding List
annotation at the same time.
A ConstraintDeclarationException
will be raised in this case.
If index
is undefined, the single constraint declaration is targeted.
@Documented
@Constraint(validatedBy = {})
@Pattern(regexp = "[A-Z0-9._%+-]+@[A-Z0-9.-]+\\.[A-Z]{2,4}") // email
@Pattern(regexp = ".*?emmanuel.*?") // emmanuel
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
public @interface EmmanuelsEmail {
String message() default "Not emmanuel's email";
@OverridesAttribute(constraint = Pattern.class, name = "message", constraintIndex = 0)
String emailMessage() default "Not an email";
@OverridesAttribute(constraint = Pattern.class, name = "message", constraintIndex = 1)
String emmanuelMessage() default "Not Emmanuel";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
EmmanuelsEmail[] value();
}
}
@OverridesAttribute
definition is as follows:
@OverridesAttribute
annotation/**
* Marks an attribute as overriding the attribute of a composing constraint.
* Both attributes must share the same type.
*
* @author Emmanuel Bernard
*/
@Documented
@Retention(RUNTIME)
@Target({ METHOD })
@Repeatable(List.class)
public @interface OverridesAttribute {
/**
* @return constraint type the attribute is overriding
*/
Class<? extends Annotation> constraint();
/**
* Name of the Constraint attribute overridden.
* Defaults to the name of the attribute hosting {@code @OverridesAttribute}.
*
* @return name of constraint attribute overridden
*/
String name() default "";
/**
* The index of the targeted constraint declaration when using
* multiple constraints of the same type.
* <p>
* The index represents the index of the constraint in the
* {@code value()} array.
* <p>
* By default, no index is defined and the single constraint declaration
* is targeted.
*
* @return constraint declaration index if multivalued annotation is used
*/
int constraintIndex() default -1;
/**
* Defines several {@link OverridesAttribute} annotations on the same element
*
* @see javax.validation.OverridesAttribute
*/
@Documented
@Target({ METHOD })
@Retention(RUNTIME)
public @interface List {
OverridesAttribute[] value();
}
}
The following elements uniquely identify an overridden constraint attribute:
-
@OverridesAttribute.constraint
-
@OverridesAttribute.name
-
@OverridesAttribute.constraintIndex
If the composition is invalid, e.g.
-
infinitely recursive composition
-
wrong attribute overriding
-
a single attribute mapped to more than one source attribute
-
a composing and composed constraint marked as different constraint types (i.e., generic and cross-parameter)
-
etc.
a ConstraintDefinitionException
is raised either at validation time or when the metadata is requested.
Constraint designers are encouraged to make use of composition (recursively or not) based on the built-in constraints defined by the specification. The composing constraints are exposed through the Bean Validation metadata API (ConstraintDescriptor). This metadata is particularly useful for third-party metadata consumers like persistence frameworks generating database schemas (such as Java Persistence) or presentation frameworks.
3.4. Constraint validation implementation
A constraint validation implementation performs the validation of a given constraint annotation for a given type. The implementation classes are specified by the validatedBy
element of the @Constraint
annotation that decorates the constraint definition. The constraint validation implementation implements the ConstraintValidator
interface.
ConstraintValidator
interface/**
* Defines the logic to validate a given constraint {@code A}
* for a given object type {@code T}.
* <p>
* Implementations must comply to the following restriction:
* <ul>
* <li>{@code T} must resolve to a non parameterized type</li>
* <li>or generic parameters of {@code T} must be unbounded
* wildcard types</li>
* </ul>
* <p>
* The annotation {@link SupportedValidationTarget} can be put on a
* {@code ConstraintValidator} implementation to mark it as supporting
* cross-parameter constraints. Check out {@link SupportedValidationTarget}
* and {@link Constraint} for more information.
*
* @param <A> the annotation type handled by an implementation
* @param <T> the target type supported by an implementation
*
* @author Emmanuel Bernard
* @author Hardy Ferentschik
*/
public interface ConstraintValidator<A extends Annotation, T> {
/**
* Initializes the validator in preparation for
* {@link #isValid(Object, ConstraintValidatorContext)} calls.
* The constraint annotation for a given constraint declaration
* is passed.
* <p>
* This method is guaranteed to be called before any use of this instance for
* validation.
* <p>
* The default implementation is a no-op.
*
* @param constraintAnnotation annotation instance for a given constraint declaration
*/
default void initialize(A constraintAnnotation) {
}
/**
* Implements the validation logic.
* The state of {@code value} must not be altered.
* <p>
* This method can be accessed concurrently, thread-safety must be ensured
* by the implementation.
*
* @param value object to validate
* @param context context in which the constraint is evaluated
*
* @return {@code false} if {@code value} does not pass the constraint
*/
boolean isValid(T value, ConstraintValidatorContext context);
}
Some restrictions apply on the generic type T
(used in the isValid()
method). T
must
-
resolve to a non parameterized type (i.e. because the type is not using generics or because the raw type is used instead of the generic version)
-
or generic parameters of
T
must be unbounded wildcard types (i.e.<?>
).
Note
|
This restriction is not a theoretical limitation and a future version of the specification might allow it. |
By default, a ConstraintValidator
targets the (returned) element annotated by the constraint. You can make a ConstraintValidator
target the array of parameters of a method or constructor (aka cross-parameter) by annotating the validator implementation with @SupportedValidationTarget
.
@SupportedValidationTarget
annotation and ValidationTarget
enumpackage javax.validation.constraintvalidation;
/**
* Defines the target(s) a {@link ConstraintValidator} can validate.
* <p>
* A {@code ConstraintValidator} can target the (returned) element
* annotated by the constraint, the array of parameters of a method
* or constructor (aka cross-parameter) or both.
* <p>
* If {@code @SupportedValidationTarget} is not present, the
* {@code ConstraintValidator} targets the (returned) element annotated
* by the constraint.
* <p>
* A {@code ConstraintValidator} targeting cross-parameter must accept
* {@code Object[]} (or {@code Object}) as the type of object it validates.
*
* @author Emmanuel Bernard
* @since 1.1
*/
@Documented
@Target({ TYPE })
@Retention(RUNTIME)
public @interface SupportedValidationTarget {
ValidationTarget[] value();
}
package javax.validation.constraintvalidation;
/**
* List of possible targets for a {@link ConstraintValidator}.
*
* @author Emmanuel Bernard
* @since 1.1
*/
public enum ValidationTarget {
/**
* (Returned) element annotated by the constraint.
*/
ANNOTATED_ELEMENT,
/**
* Array of parameters of the annotated method or constructor (aka cross-parameter).
*/
PARAMETERS
}
A ConstraintValidator
implementation can target both annotated elements and array of parameters.
If a ConstraintValidator
targets array of parameters (cross-parameter), T
must resolve to Object[]
(or Object
) in order to have the array of parameter values passed to the isValid()
method. A ConstraintDefinitionException
is raised otherwise.
@SupportedValidationTarget(ValidationTarget.PARAMETERS)
public class ScriptAssertValidator implements ConstraintValidator<ScriptAssert,Object[]> {
@Override
public void initialize(ScriptAssert constraintAnnotation) {
[...]
}
@Override
public boolean isValid(Object[] value, ConstraintValidatorContext context) {
[...]
}
}
Valid ConstraintValidator definitions shows some examples of valid definitions.
//String is not making use of generics
public class SizeValidatorForString implements ConstraintValidator<Size, String> {
[...]
}
//Collection uses generics but the raw type is used
public class SizeValidatorForCollection implements ConstraintValidator<Size, Collection> {
[...]
}
//Collection uses generics and unbounded wildcard type
public class SizeValidatorForCollection implements ConstraintValidator<Size, Collection<?>> {
[...]
}
//Validator for cross-parameter constraint
@SupportedValidationTarget(ValidationTarget.PARAMETERS)
public class DateParametersConsistentValidator
implements ConstraintValidator<DateParametersConsistent, Object[]> {
[...]
}
//Validator for both annotated elements and executable parameters
@SupportedValidationTarget({ValidationTarget.ANNOTATED_ELEMENT, ValidationTarget.PARAMETERS})
public class ELScriptValidator implements ConstraintValidator<ELScript, Object> {
[...]
}
And some invalid definitions in Invalid ConstraintValidator definitions.
//parameterized type
public class SizeValidatorForString implements ConstraintValidator<Size, Collection<String>> {
[...]
}
//parameterized type using bounded wildcard
public class SizeValidatorForCollection implements ConstraintValidator<Size, Collection<? extends Address>> {
[...]
}
//cross-parameter validator accepting the wrong type
@SupportedValidationTarget(ValidationTarget.PARAMETERS)
public class NumberPositiveValidator implements ConstraintValidator<NumberPositive, Number> {
[...]
}
The lifecycle of a constraint validation implementation instance is undefined. Bean Validation providers are allowed to cache ConstraintValidator
instances retrieved from the ConstraintValidatorFactory
.
The initialize()
method is called by the Bean validation provider prior to any use of the constraint implementation.
As of Bean Validation 2.0, initialize()
has an empty default implementation,
allowing to omit the implementation from validators that don’t need to access any constraint attributes.
The isValid()
method is evaluated by the Bean Validation provider each time a given value is validated. It returns false
if the value is not valid, true
otherwise. isValid()
implementations must be thread-safe.
If the property is of an unanticipated type, an UnexpectedTypeException
is raised. ConstraintValidator
implementations raise this exception themselves if they receive an unsupported type. However, constraint designers are encouraged to make use of specialized ConstraintValidator
implementations and delegate the type resolution to the Bean Validation provider (see the type matching algorithm described in ConstraintValidator resolution algorithm).
If an exception occurs either in the initialize()
or isValid()
method, the runtime exception is wrapped into a ValidationException
by the Bean Validation engine.
The constraint validation implementation is not allowed to change the state of the value passed to isValid()
.
Note
|
While not mandatory, it is considered a good practice to split the core constraint validation from the not null constraint validation (for example, an
|
The ConstraintValidatorContext
object passed to the isValid()
method carries information and operations available in the context the constraint is validated to.
ConstraintValidatorContext
interface/**
* Provides contextual data and operation when applying a given constraint validator.
*
* At least one {@link ConstraintViolation} must be defined (either the default one,
* of if the default {@code ConstraintViolation} is disabled, a custom one).
*
* @author Emmanuel Bernard
* @author Guillaume Smet
*/
public interface ConstraintValidatorContext {
/**
* Disables the default {@link ConstraintViolation} object generation (which
* is using the message template declared on the constraint).
* <p>
* Useful to set a different violation message or generate a {@code ConstraintViolation}
* based on a different property.
*/
void disableDefaultConstraintViolation();
/**
* @return the current un-interpolated default message
*/
String getDefaultConstraintMessageTemplate();
/**
* Returns the provider for obtaining the current time in the form of a {@link Clock},
* e.g. when validating the {@code Future} and {@code Past} constraints.
*
* @return the provider for obtaining the current time, never {@code null}. If no
* specific provider has been configured during bootstrap, a default implementation using
* the current system time and the current default time zone as returned by
* {@link Clock#systemDefaultZone()} will be returned.
*
* @since 2.0
*/
ClockProvider getClockProvider();
/**
* Returns a constraint violation builder building a violation report
* allowing to optionally associate it to a sub path.
* The violation message will be interpolated.
* <p>
* To create the {@link ConstraintViolation}, one must call either one of
* the {@code addConstraintViolation()} methods available in one of the
* interfaces of the fluent API.
* If another method is called after {@code addConstraintViolation()} on
* {@code ConstraintViolationBuilder} or any of its associated nested interfaces
* an {@code IllegalStateException} is raised.
* <p>
* If {@link ConstraintValidator#isValid(Object, ConstraintValidatorContext)} returns
* {@code false}, a {@code ConstraintViolation} object will be built per constraint
* violation report including the default one (unless
* {@link #disableDefaultConstraintViolation()} has been called).
* <p>
* {@code ConstraintViolation} objects generated from such a call
* contain the same contextual information (root bean, path and so on) unless
* the path has been overridden.
* <p>
* To create a different {@code ConstraintViolation}, a new constraint violation builder
* has to be retrieved from {@code ConstraintValidatorContext}
*
* Here are a few usage examples:
* <pre>
* //assuming the following domain model
* public class User {
* public Map<String,Address> getAddresses() { ... }
* }
*
* public class Address {
* public String getStreet() { ... }
* public Country getCountry() { ... }
* }
*
* public class Country {
* public String getName() { ... }
* }
*
* //From a property-level constraint on User.addresses
* //Build a constraint violation on the default path - i.e. the "addresses" property
* context.buildConstraintViolationWithTemplate( "this detail is wrong" )
* .addConstraintViolation();
*
* //From a class level constraint on Address
* //Build a constraint violation on the default path + "street"
* //i.e. the street property of Address
* context.buildConstraintViolationWithTemplate( "this detail is wrong" )
* .addPropertyNode( "street" )
* .addConstraintViolation();
*
* //From a property-level constraint on User.addresses
* //Build a constraint violation on the default path + the bean stored
* //under the "home" key in the map
* context.buildConstraintViolationWithTemplate( "Incorrect home address" )
* .addBeanNode()
* .inContainer( Map.class, 1 )
* .inIterable().atKey( "home" )
* .addConstraintViolation();
*
* //From a class level constraint on User
* //Build a constraint violation on the default path + addresses["home"].country.name
* //i.e. property "country.name" on the object stored under "home" in the map
* context.buildConstraintViolationWithTemplate( "this detail is wrong" )
* .addPropertyNode( "addresses" )
* .addPropertyNode( "country" )
* .inContainer( Map.class, 1 )
* .inIterable().atKey( "home" )
* .addPropertyNode( "name" )
* .addConstraintViolation();
*
* //From a class level constraint on User
* //Build a constraint violation on the default path + addresses["home"].<map key>
* //i.e. a container element constraint violation for the map key
* context.buildConstraintViolationWithTemplate( "the map key is invalid" )
* .addPropertyNode( "addresses" )
* .addContainerElementNode( "<map key>", Map.class, 0 )
* .inIterable().atKey( "invalid" )
* .addConstraintViolation();
* </pre>
* <p>
* Cross-parameter constraints on a method can create a node specific
* to a particular parameter if required. Let's explore a few examples:
* <pre>
* //Cross-parameter constraint on method
* //createUser(String password, String passwordRepeat)
* //Build a constraint violation on the default path + "passwordRepeat"
* context.buildConstraintViolationWithTemplate("Passwords do not match")
* .addParameterNode(1)
* .addConstraintViolation();
*
* //Cross-parameter constraint on a method
* //mergeAddresses(Map<String,Address> addresses,
* // Map<String,Address> otherAddresses)
* //Build a constraint violation on the default path + "otherAddresses["home"]
* //i.e. the Address bean hosted in the "home" key of the "otherAddresses" map parameter
* context.buildConstraintViolationWithTemplate(
* "Map entry home present in both and does not match")
* .addParameterNode(1)
* .addBeanNode()
* .inContainer( Map.class, 1 )
* .inIterable().atKey("home")
* .addConstraintViolation();
*
* //Cross-parameter constraint on a method
* //mergeAddresses(Map<String,Address> addresses,
* // Map<String,Address> otherAddresses)
* //Build a constraint violation on the default path + "otherAddresses["home"].city
* //i.e. on the "city" property of the Address bean hosted in
* //the "home" key of the "otherAddresses" map
* context.buildConstraintViolationWithTemplate(
* "Map entry home present in both but city does not match")
* .addParameterNode(1)
* .addPropertyNode("city")
* .inContainer( Map.class, 1 )
* .inIterable().atKey("home")
* .addConstraintViolation();
* </pre>
*
* @param messageTemplate new un-interpolated constraint message
* @return returns a constraint violation builder
*/
ConstraintViolationBuilder buildConstraintViolationWithTemplate(String messageTemplate);
/**
* Returns an instance of the specified type allowing access to
* provider-specific APIs. If the Bean Validation provider
* implementation does not support the specified class,
* {@link ValidationException} is thrown.
*
* @param type the class of the object to be returned
* @param <T> the type of the object to be returned
* @return an instance of the specified class
* @throws ValidationException if the provider does not support the call
*
* @since 1.1
*/
<T> T unwrap(Class<T> type);
/**
* {@link ConstraintViolation} builder allowing to optionally associate
* the violation report to a sub path.
* <p>
* To create the {@code ConstraintViolation}, one must call either one of
* the {@code addConstraintViolation()} methods available in one of the
* interfaces of the fluent API.
* <p>
* If another method is called after {@code addConstraintViolation()} on
* {@code ConstraintViolationBuilder} or any of its associated objects
* an {@code IllegalStateException} is raised.
*/
interface ConstraintViolationBuilder {
/**
* Adds a node to the path the {@link ConstraintViolation} will be associated to.
* <p>
* {@code name} describes a single property. In particular,
* dot (.) is not allowed.
*
* @param name property name
* @return a builder representing node {@code name}
* @deprecated since 1.1 - replaced by {@link #addPropertyNode(String)},
* {@link #addBeanNode()} and {@link #addParameterNode(int)}
*/
NodeBuilderDefinedContext addNode(String name);
/**
* Adds a property node to the path the {@link ConstraintViolation}
* will be associated to.
* <p>
* {@code name} describes a single property. In particular,
* dot (.) is not allowed.
*
* @param name property name
* @return a builder representing node {@code name}
* @throws IllegalArgumentException if the name is null
*
* @since 1.1
*/
NodeBuilderCustomizableContext addPropertyNode(String name);
/**
* Adds a bean node (class-level) to the path the {@link ConstraintViolation}
* will be associated to.
* Note that bean nodes are always leaf nodes.
*
* @return a builder representing the bean node
*
* @since 1.1
*/
LeafNodeBuilderCustomizableContext addBeanNode();
/**
* Adds a container element node to the path the {@link ConstraintViolation}
* will be associated to.
*
* @param name the node name
* @param containerType the type of the container
* @param typeArgumentIndex the index of the type argument
* @return a builder representing the container element node
* @throws IllegalArgumentException if the index is not valid
*
* @since 2.0
*/
ContainerElementNodeBuilderCustomizableContext addContainerElementNode(String name,
Class<?> containerType, Integer typeArgumentIndex);
/**
* Adds a method parameter node to the path the {@link ConstraintViolation}
* will be associated to.
* The parameter index must be valid (i.e. within the boundaries of the method
* parameter indexes). May only be called from within cross-parameter validators.
*
* @param index the parameter index
* @return a builder representing the index-th parameter node
* @throws IllegalArgumentException if the index is not valid
*
* @since 1.1
*/
NodeBuilderDefinedContext addParameterNode(int index);
/**
* Adds the new {@link ConstraintViolation} to be generated if the
* constraint validator marks the value as invalid.
* <p>
* Methods of this {@code ConstraintViolationBuilder} instance and its nested
* objects throw {@code IllegalStateException} from now on.
*
* @return the {@code ConstraintValidatorContext} instance the
* {@code ConstraintViolationBuilder} comes from
*/
ConstraintValidatorContext addConstraintViolation();
/**
* Represents a node whose context is known
* (i.e. index, key and isInIterable)
* and that is a leaf node (i.e. no subnode can be added).
*
* @since 1.1
*/
interface LeafNodeBuilderDefinedContext {
/**
* Adds the new {@link ConstraintViolation} to be generated if the
* constraint validator marks the value as invalid.
* <p>
* Methods of the {@code ConstraintViolationBuilder} instance this object
* comes from and the constraint violation builder nested
* objects throw {@code IllegalStateException} after this call.
*
* @return {@code ConstraintValidatorContext} instance the
* {@code ConstraintViolationBuilder} comes from
*/
ConstraintValidatorContext addConstraintViolation();
}
/**
* Represents a node whose context is
* configurable (i.e. index, key and isInIterable)
* and that is a leaf node (i.e. no subnode can be added).
*
* @since 1.1
*/
interface LeafNodeBuilderCustomizableContext {
/**
* Marks the node as being in an iterable, e.g. array, {@code Iterable} or a
* {@code Map}.
*
* @return a builder representing iterable details
*/
LeafNodeContextBuilder inIterable();
/**
* Marks the node as being in a container such as a {@code List}, {@code Map} or
* {@code Optional}.
*
* @param containerClass the type of the container
* @param typeArgumentIndex type index of the concerned type argument
* @return a builder representing the current node
* @throws IllegalArgumentException if the index is not valid
*
* @since 2.0
*/
LeafNodeBuilderCustomizableContext inContainer(Class<?> containerClass,
Integer typeArgumentIndex);
/**
* Adds the new {@link ConstraintViolation} to be generated if the
* constraint validator mark the value as invalid.
* <p>
* Methods of the {@code ConstraintViolationBuilder} instance this object
* comes from and the constraint violation builder nested
* objects throw {@code IllegalStateException} after this call.
*
* @return {@code ConstraintValidatorContext} instance the
* {@code ConstraintViolationBuilder} comes from
*/
ConstraintValidatorContext addConstraintViolation();
}
/**
* Represents refinement choices for a node which is
* in an iterable, e.g. array, {@code Iterable} or {@code Map}.
* <p>
* If the iterable is an indexed collection or a map,
* the index or the key should be set.
* <p>
* The node is a leaf node (i.e. no subnode can be added).
*
* @since 1.1
*/
interface LeafNodeContextBuilder {
/**
* Defines the key the object is into the {@code Map}.
*
* @param key map key
* @return a builder representing the current node
*/
LeafNodeBuilderDefinedContext atKey(Object key);
/**
* Defines the index the object is into the {@code List} or array
*
* @param index index
* @return a builder representing the current node
*/
LeafNodeBuilderDefinedContext atIndex(Integer index);
/**
* Adds the new {@link ConstraintViolation} to be generated if the
* constraint validator mark the value as invalid.
* <p>
* Methods of the {@code ConstraintViolationBuilder} instance this object
* comes from and the constraint violation builder nested
* objects throw {@code IllegalStateException} after this call.
*
* @return {@code ConstraintValidatorContext} instance the
* {@code ConstraintViolationBuilder} comes from
*/
ConstraintValidatorContext addConstraintViolation();
}
/**
* Represents a node whose context is known
* (i.e. index, key and isInIterable)
* and that is not necessarily a leaf node (i.e. subnodes can
* be added).
*/
interface NodeBuilderDefinedContext {
/**
* Adds a node to the path the {@link ConstraintViolation} will be associated to.
* <p>
* {@code name} describes a single property. In particular,
* dot (.) is not allowed.
*
* @param name property name
* @return a builder representing node {@code name}
* @deprecated since 1.1 - replaced by {@link #addPropertyNode(String)}
* and {@link #addBeanNode()}
*/
NodeBuilderCustomizableContext addNode(String name);
/**
* Adds a property node to the path the {@link ConstraintViolation}
* will be associated to.
* <p>
* {@code name} describes a single property. In particular,
* dot (.) is not allowed.
*
* @param name property name
* @return a builder representing node {@code name}
* @throws IllegalArgumentException if the name is null
*
* @since 1.1
*/
NodeBuilderCustomizableContext addPropertyNode(String name);
/**
* Adds a bean node (class-level) to the path the {@link ConstraintViolation}
* will be associated to.
* Note that bean nodes are always leaf nodes.
*
* @return a builder representing the bean node
*
* @since 1.1
*/
LeafNodeBuilderCustomizableContext addBeanNode();
/**
* Adds a container element node to the path the {@link ConstraintViolation}
* will be associated to.
*
* @param name the node name
* @param containerType the type of the container
* @param typeArgumentIndex the index of the type argument
* @return a builder representing the container element node
* @throws IllegalArgumentException if the index is not valid
*
* @since 2.0
*/
ContainerElementNodeBuilderCustomizableContext addContainerElementNode(
String name, Class<?> containerType, Integer typeArgumentIndex);
/**
* Adds the new {@link ConstraintViolation} to be generated if the
* constraint validator marks the value as invalid.
* <p>
* Methods of the {@code ConstraintViolationBuilder} instance this object
* comes from and the constraint violation builder nested
* objects throw {@code IllegalStateException} after this call.
*
* @return {@code ConstraintValidatorContext} instance the
* {@code ConstraintViolationBuilder} comes from
*/
ConstraintValidatorContext addConstraintViolation();
}
/**
* Represents a node whose context is
* configurable (i.e. index, key and isInIterable)
* and that is not necessarily a leaf node (i.e. subnodes can
* be added).
*/
interface NodeBuilderCustomizableContext {
/**
* Marks the node as being in an iterable, e.g. array, {@code Iterable} or a
* {@code Map}.
*
* @return a builder representing iterable details
*/
NodeContextBuilder inIterable();
/**
* Marks the node as being in a container such as a {@code List}, {@code Map} or
* {@code Optional}.
*
* @param containerClass the type of the container
* @param typeArgumentIndex type index of the concerned type argument
* @return a builder representing the current node
* @throws IllegalArgumentException if the index is not valid
*
* @since 2.0
*/
NodeBuilderCustomizableContext inContainer(Class<?> containerClass,
Integer typeArgumentIndex);
/**
* Adds a node to the path the {@link ConstraintViolation} will be associated to.
*
* {@code name} describes a single property. In particular,
* dot (.) is not allowed.
*
* @param name property name
* @return a builder representing node {@code name}
* @deprecated since 1.1 - replaced by {@link #addPropertyNode(String)}
* and {@link #addBeanNode()}
*/
NodeBuilderCustomizableContext addNode(String name);
/**
* Adds a property node to the path the {@link ConstraintViolation}
* will be associated to.
*
* {@code name} describes a single property. In particular,
* dot (.) is not allowed.
*
* @param name property name
* @return a builder representing node {@code name}
* @throws IllegalArgumentException if the name is null
*
* @since 1.1
*/
NodeBuilderCustomizableContext addPropertyNode(String name);
/**
* Adds a bean node (class-level) to the path the {@link ConstraintViolation}
* will be associated to.
* Note that bean nodes are always leaf nodes.
*
* @return a builder representing the bean node
*
* @since 1.1
*/
LeafNodeBuilderCustomizableContext addBeanNode();
/**
* Adds a container element node to the path the {@link ConstraintViolation}
* will be associated to.
*
* @param name the node name
* @param containerType the type of the container
* @param typeArgumentIndex the index of the type argument
* @return a builder representing the container element node
* @throws IllegalArgumentException if the index is not valid
*
* @since 2.0
*/
ContainerElementNodeBuilderCustomizableContext addContainerElementNode(
String name, Class<?> containerType, Integer typeArgumentIndex);
/**
* Adds the new {@link ConstraintViolation} to be generated if the
* constraint validator mark the value as invalid.
* <p>
* Methods of the {@code ConstraintViolationBuilder} instance this object
* comes from and the constraint violation builder nested
* objects throw {@code IllegalStateException} after this call.
*
* @return {@code ConstraintValidatorContext} instance the
* {@code ConstraintViolationBuilder} comes from
*/
ConstraintValidatorContext addConstraintViolation();
}
/**
* Represents refinement choices for a node which is
* in an iterable, e.g. array, {@code Iterable} or {@code Map}.
* <p>
* If the iterable is an indexed collection or a map,
* the index or the key should be set.
* <p>
* The node is not necessarily a leaf node (i.e. subnodes can
* be added).
*/
interface NodeContextBuilder {
/**
* Defines the key the object is into the {@code Map}.
*
* @param key map key
* @return a builder representing the current node
*/
NodeBuilderDefinedContext atKey(Object key);
/**
* Defines the index the object is into the {@code List} or array.
*
* @param index index
* @return a builder representing the current node
*/
NodeBuilderDefinedContext atIndex(Integer index);
/**
* Adds a node to the path the {@code ConstraintViolation} will be associated to.
*
* {@code name} describes a single property. In particular,
* dot (.) is not allowed.
*
* @param name property name
* @return a builder representing node {@code name}
* @deprecated since 1.1 - replaced by {@link #addPropertyNode(String)}
* and {@link #addBeanNode()}
*/
NodeBuilderCustomizableContext addNode(String name);
/**
* Adds a property node to the path the {@link ConstraintViolation}
* will be associated to.
*
* {@code name} describes a single property. In particular,
* dot (.) is not allowed.
*
* @param name property name
* @return a builder representing node {@code name}
* @throws IllegalArgumentException if the name is null
*
* @since 1.1
*/
NodeBuilderCustomizableContext addPropertyNode(String name);
/**
* Adds a bean node (class-level) to the path the {@link ConstraintViolation}
* will be associated to.
* <p>
* Note that bean nodes are always leaf nodes.
*
* @return a builder representing the bean node
*
* @since 1.1
*/
LeafNodeBuilderCustomizableContext addBeanNode();
/**
* Adds a container element node to the path the {@link ConstraintViolation}
* will be associated to.
*
* @param name the node name
* @param containerType the type of the container
* @param typeArgumentIndex the index of the type argument
* @return a builder representing the container element node
* @throws IllegalArgumentException if the index is not valid
*
* @since 2.0
*/
ContainerElementNodeBuilderCustomizableContext addContainerElementNode(
String name, Class<?> containerType, Integer typeArgumentIndex);
/**
* Adds the new {@link ConstraintViolation} to be generated if the
* constraint validator mark the value as invalid.
* <p>
* Methods of the {@code ConstraintViolationBuilder} instance this object
* comes from and the constraint violation builder nested
* objects throw {@code IllegalStateException} after this call.
*
* @return {@code ConstraintValidatorContext} instance the
* {@code ConstraintViolationBuilder} comes from
*/
ConstraintValidatorContext addConstraintViolation();
}
/**
* Represents a container element node whose context is known
* (i.e. index, key and isInIterable)
* and that is not necessarily a leaf node (i.e. subnodes can
* be added).
*
* @since 2.0
*/
interface ContainerElementNodeBuilderDefinedContext {
/**
* Adds a property node to the path the {@link ConstraintViolation}
* will be associated to.
* <p>
* {@code name} describes a single property. In particular,
* dot (.) is not allowed.
*
* @param name property name
* @return a builder representing node {@code name}
* @throws IllegalArgumentException if the name is null
*/
NodeBuilderCustomizableContext addPropertyNode(String name);
/**
* Adds a bean node (class-level) to the path the {@link ConstraintViolation}
* will be associated to.
* Note that bean nodes are always leaf nodes.
*
* @return a builder representing the bean node
*/
LeafNodeBuilderCustomizableContext addBeanNode();
/**
* Adds a container element node to the path the {@link ConstraintViolation}
* will be associated to.
*
* @param name the node name
* @param containerType the type of the container
* @param typeArgumentIndex the index of the type argument
* @return a builder representing the container element node
* @throws IllegalArgumentException if the index is not valid
*/
ContainerElementNodeBuilderCustomizableContext addContainerElementNode(
String name, Class<?> containerType, Integer typeArgumentIndex);
/**
* Adds the new {@link ConstraintViolation} to be generated if the
* constraint validator marks the value as invalid.
* <p>
* Methods of the {@code ConstraintViolationBuilder} instance this object
* comes from and the constraint violation builder nested
* objects throw {@code IllegalStateException} after this call.
*
* @return {@code ConstraintValidatorContext} instance the
* {@code ConstraintViolationBuilder} comes from
*/
ConstraintValidatorContext addConstraintViolation();
}
/**
* Represents a container element node whose context is
* configurable (i.e. index, key and isInIterable)
* and that is not necessarily a leaf node (i.e. subnodes can
* be added).
*
* @since 2.0
*/
interface ContainerElementNodeBuilderCustomizableContext {
/**
* Marks the node as being in an iterable, e.g. array, {@code Iterable} or a
* {@code Map}.
*
* @return a builder representing iterable details
*/
ContainerElementNodeContextBuilder inIterable();
/**
* Adds a property node to the path the {@link ConstraintViolation}
* will be associated to.
*
* {@code name} describes a single property. In particular,
* dot (.) is not allowed.
*
* @param name property name
* @return a builder representing node {@code name}
* @throws IllegalArgumentException if the name is null
*/
NodeBuilderCustomizableContext addPropertyNode(String name);
/**
* Adds a bean node (class-level) to the path the {@link ConstraintViolation}
* will be associated to.
* <p>
* Note that bean nodes are always leaf nodes.
*
* @return a builder representing the bean node
*/
LeafNodeBuilderCustomizableContext addBeanNode();
/**
* Adds a container element node to the path the {@link ConstraintViolation}
* will be associated to.
*
* @param name the node name
* @param containerType the type of the container
* @param typeArgumentIndex the index of the type argument
* @return a builder representing the container element node
* @throws IllegalArgumentException if the index is not valid
*/
ContainerElementNodeBuilderCustomizableContext addContainerElementNode(
String name, Class<?> containerType, Integer typeArgumentIndex);
/**
* Adds the new {@link ConstraintViolation} to be generated if the
* constraint validator mark the value as invalid.
* <p>
* Methods of the {@code ConstraintViolationBuilder} instance this object
* comes from and the constraint violation builder nested
* objects throw {@code IllegalStateException} after this call.
*
* @return {@code ConstraintValidatorContext} instance the
* {@code ConstraintViolationBuilder} comes from
*/
ConstraintValidatorContext addConstraintViolation();
}
/**
* Represents refinement choices for a container element node.
* <p>
* If the container is an indexed collection or a map,
* the index or the key should be set.
* <p>
* The node is not necessarily a leaf node (i.e. subnodes can
* be added).
*
* @since 2.0
*/
interface ContainerElementNodeContextBuilder {
/**
* Defines the key the object is into the {@code Map}.
*
* @param key map key
* @return a builder representing the current node
*/
ContainerElementNodeBuilderDefinedContext atKey(Object key);
/**
* Defines the index the object is into the {@code List} or array.
*
* @param index index
* @return a builder representing the current node
*/
ContainerElementNodeBuilderDefinedContext atIndex(Integer index);
/**
* Adds a property node to the path the {@link ConstraintViolation}
* will be associated to.
*
* {@code name} describes a single property. In particular,
* dot (.) is not allowed.
*
* @param name property name
* @return a builder representing node {@code name}
* @throws IllegalArgumentException if the name is null
*/
NodeBuilderCustomizableContext addPropertyNode(String name);
/**
* Adds a bean node (class-level) to the path the {@link ConstraintViolation}
* will be associated to.
* <p>
* Note that bean nodes are always leaf nodes.
*
* @return a builder representing the bean node
*/
LeafNodeBuilderCustomizableContext addBeanNode();
/**
* Adds a container element node to the path the {@link ConstraintViolation}
* will be associated to.
*
* @param name the node name
* @param containerType the type of the container
* @param typeArgumentIndex the index of the type argument
* @return a builder representing the container element node
* @throws IllegalArgumentException if the index is not valid
*/
ContainerElementNodeBuilderCustomizableContext addContainerElementNode(
String name, Class<?> containerType, Integer typeArgumentIndex);
/**
* Adds the new {@link ConstraintViolation} to be generated if the
* constraint validator mark the value as invalid.
* <p>
* Methods of the {@code ConstraintViolationBuilder} instance this object
* comes from and the constraint violation builder nested
* objects throw {@code IllegalStateException} after this call.
*
* @return {@code ConstraintValidatorContext} instance the
* {@code ConstraintViolationBuilder} comes from
*/
ConstraintValidatorContext addConstraintViolation();
}
}
}
The ConstraintValidatorContext
interface provides access to contextual information useful for the validation of specific constraints (e.g. getClockProvider()
, see Implementation of temporal constraint validators ).
It also allows redefinition of the default constraint message generated when a constraint is not valid. By default, each invalid constraint leads to the generation of one error object represented by a ConstraintViolation
object.
This object is built from the default constraint message template as defined by the constraint declaration and the context in which the constraint declaration is placed (bean, property, executable parameter, cross-parameter, executable return value or container element).
The ConstraintValidatorContext
methods let the constraint implementation disable the default ConstraintViolation
generation and create one or more custom ones. The non-interpolated message passed as a parameter is used to build the ConstraintViolation
message (the message interpolation operation is applied to it).
By default, the Path
exposed on the ConstraintViolation
represents the path to the bean, property, parameter, cross-parameter, return value or container element hosting the constraint (see ConstraintViolation for more information). You can point it to a subpath of this default path by using the constraint violation builder fluent API.
Using the fluent API to build custom constraint violations shows a few examples.
//assuming the following domain model
public class User {
public Map<String,Address> getAddresses() { [...] }
}
public class Address {
public String getStreet() { [...] }
public Country getCountry() { [...] }
}
public class Country {
public String getName() { [...] }
}
//From a property-level constraint on User.addresses
//Build a constraint violation on the default path - i.e. the "addresses" property
context.buildConstraintViolationWithTemplate( "this detail is wrong" )
.addConstraintViolation();
//From a class level constraint on Address
//Build a constraint violation on the default path + "street"
//i.e. the street property of Address
context.buildConstraintViolationWithTemplate( "this detail is wrong" )
.addPropertyNode( "street" )
.addConstraintViolation();
//From a property-level constraint on User.addresses
//Build a constraint violation on the default path + the bean stored
//under the "home" key in the map
context.buildConstraintViolationWithTemplate( "Incorrect home address" )
.addBeanNode()
.inContainer( Map.class, 1 )
.inIterable().atKey( "home" )
.addConstraintViolation();
//From a class level constraint on User
//Build a constraint violation on the default path + addresses["home"].country.name
//i.e. property "country.name" on the object stored under "home" in the map
context.buildConstraintViolationWithTemplate( "this detail is wrong" )
.addPropertyNode( "addresses" )
.addPropertyNode( "country" )
.inContainer( Map.class, 1 )
.inIterable().atKey( "home" )
.addPropertyNode( "name" )
.addConstraintViolation();
//From a class level constraint on User
//Build a constraint violation on the default path + addresses["home"].<map key>
//i.e. a container element constraint violation for the map key
context.buildConstraintViolationWithTemplate( "the map key is invalid" )
.addPropertyNode( "addresses" )
.addContainerElementNode( "<map key>", Map.class, 0 )
.inIterable().atKey( "home" )
.addConstraintViolation();
//To create a subnode representing a method parameter from a cross-parameter constraint violation
//Cross-parameter constraint on method createUser(String password, String passwordRepeat)
//Build a constraint violation on the default path + "passwordRepeat"
context.buildConstraintViolationWithTemplate("Passwords do not match")
.addParameterNode( 1 )
.addConstraintViolation();
//Cross-parameter constraint on a method
//mergeAddresses(Map<String,Address> addresses, Map<String,Address> otherAddresses)
//Build a constraint violation on the default path + "otherAddresses["home"]
//i.e. the Address bean hosted in the "home" key of the "otherAddresses" map parameter
context.buildConstraintViolationWithTemplate(
"Map entry home present in both and does not match" )
.addParameterNode( 1 )
.addBeanNode()
.inContainer( Map.class, 1 )
.inIterable().atKey( "home" )
.addConstraintViolation();
//Cross-parameter constraint on a method
//mergeAddresses(Map<String,Address> addresses, Map<String,Address> otherAddresses)
//Build a constraint violation on the default path + "otherAddresses["home"].city
//i.e. on the "city" property of the Address bean hosted in
//the "home" key of the "otherAddresses" map
context.buildConstraintViolationWithTemplate(
"Map entry home present in both but city does not match" )
.addParameterNode( 1 )
.addPropertyNode( "city" )
.inContainer( Map.class, 1 )
.inIterable().atKey( "home" )
.addConstraintViolation();
If disableDefaultConstraintViolation()
is called, no custom error is added (using the error builder) and if the constraint is not valid, a ValidationException
is raised.
3.4.1. Implementation of temporal constraint validators
Constraint validators for temporal constraints (either the built-in constraints @Past
, @PastOrPresent
, @Future
and @FutureOrPresent
or custom temporal constraints) can obtain the current instant from the ClockProvider
object exposed by ConstraintValidatorContext#getClockProvider()
.
ClockProvider
interface/**
* Contract for obtaining the {@link Clock} used as the reference for {@code now} when
* validating the {@code @Future} and {@code @Past} constraints.
* <p>
* The default implementation will return the current system time. Plugging in custom
* implementations may be useful for instance in batch applications which need to run with a
* specific logical date, e.g. with yesterday's date when re-running a failed batch job
* execution.
* <p>
* Implementations must be safe for access from several threads at the same time.
*
* @author Gunnar Morling
* @author Guillaume Smet
* @since 2.0
*/
public interface ClockProvider {
/**
* Returns the clock which serves as the reference for {@code now}.
*
* @return the clock which serves as the reference for {@code now}; must not be
* {@code null}
*/
Clock getClock();
}
The getClock()
method returns a java.time.Clock
object which represents the current instant, date and time using a time zone.
A conforming Bean Validation implementation provides a default clock provider which returns a clock representing the current system time and default time zone.
It is recommended that implementations call Clock#systemDefaultZone()
to obtain the clock.
When bootstrapping a validator factory or validator, an alternative clock provider can be registered (see Bootstrapping). This can for instance be useful for testing, for applying the time zone of the currently logged in user in a multi-user, multi time zone application or for running batch applications with a logical date and time different from the actual current date and time.
3.4.2. Examples
/**
* Check that a String begins with one of the given prefixes.
*/
public class BeginsWithValidator implements ConstraintValidator<BeginsWith, String> {
private Set<String> allowedPrefixes;
/**
* Configure the constraint validator based on the elements specified at the time it was
* defined.
*
* @param constraint the constraint definition
*/
@Override
public void initialize(BeginsWith constraint) {
allowedPrefixes = Arrays.stream( constraint.value() )
.collect( collectingAndThen( toSet(), Collections::unmodifiableSet ) );
}
/**
* Validate a specified value. returns false if the specified value does not conform to
* the definition.
*/
@Override
public boolean isValid(String value, ConstraintValidatorContext context) {
if ( value == null )
return true;
return allowedPrefixes.stream()
.anyMatch( value::startsWith );
}
}
This ConstraintValidator
checks that a String begins with one of the accepted prefixes.
It also demonstrates an interesting best practice: return true
on a null parameter.
The following listing shows a validator implementing the validation logic for a cross-parameter constraint.
/**
* Check that two date parameters of a method are in the expected order. Expects the 2nd and
* 3rd parameter of the validated method to be of type java.util.Date.
*/
@SupportedValidationTarget(ValidationTarget.PARAMETERS)
public class DateParametersConsistentValidator implements
ConstraintValidator<DateParametersConsistent, Object[]> {
/**
* Validate a specified value. returns false if the specified value does not conform to
* the definition
*/
@Override
public boolean isValid(Object[] value, ConstraintValidatorContext context) {
if ( value.length != 3 ) {
throw new IllegalArgumentException( "Unexpected method signature" );
}
// one or both limits are unbounded => always consistent
if ( value[1] == null || value[2] == null ) {
return true;
}
return ( (Date) value[1] ).before( (Date) value[2] );
}
}
The following listing shows a validator implementing the validation logic for a constraint that is both generic and cross-parameter.
/**
* Checks that an object passes the Expression Language expression
* provided by the constraint.
*/
@SupportedValidationTarget({ValidationTarget.ANNOTATED_ELEMENT, ValidationTarget.PARAMETERS})
public class ELScriptValidator implements ConstraintValidator<ELScript, Object> {
public void initialize(ELScript constraint) {
[...]
}
public boolean isValid(Object value, ConstraintValidatorContext context) {
[...]
}
}
The next example shows how to use ConstraintValidatorContext
.
/**
* Check that a String begins with "SN-" and has a specified length.
* <p>
* Error messages are using either key:
* <ul>
* <li>com.acme.constraint.SerialNumber.wrongprefix if the string doesn't begin with
* "SN-"</li>
* <li>com.acme.constraint.SerialNumber.wronglength if the string doesn't have the
* specified length</li>
* </ul>
*/
public class SerialNumberValidator implements ConstraintValidator<SerialNumber, String> {
private int length;
/**
* Configure the constraint validator based on the elements specified at the time it was
* defined.
*
* @param constraint the constraint definition
*/
@Override
public void initialize(SerialNumber constraint) {
this.length = constraint.length();
}
/**
* Validate a specified value. returns false if the specified value does not conform to
* the definition.
*/
@Override
public boolean isValid(String value, ConstraintValidatorContext context) {
if ( value == null )
return true;
context.disableDefaultConstraintViolation();
if ( !value.startsWith( "SN-" ) ) {
String wrongPrefix = "{com.acme.constraint.SerialNumber.wrongprefix}";
context.buildConstraintViolationWithTemplate( wrongPrefix )
.addConstraintViolation();
return false;
}
if ( value.length() != length ) {
String wrongLength = "{com.acme.constraint.SerialNumber.wronglength}";
context.buildConstraintViolationWithTemplate( wrongLength )
.addConstraintViolation();
return false;
}
return true;
}
}
The default error message is disabled and replaced by a specific error message depending on the type of constraint violation detected. In this case, only one error report is returned at a given time but a constraint validation implementation can return several error reports.
The following example shows how to obtain the current date and time via the ClockProvider
when validating a temporal constraint such as @Past
:
/**
* Validates that the given {@link ZonedDateTime} is in the past.
*/
public class PastValidatorForZonedDateTime implements ConstraintValidator<Past, ZonedDateTime> {
@Override
public boolean isValid(ZonedDateTime value, ConstraintValidatorContext context) {
if ( value == null ) {
return true;
}
ZonedDateTime now = ZonedDateTime.now( context.getClockProvider().getClock() );
return value.isBefore( now );
}
}
3.5. The ConstraintValidatorFactory
Constraint validation implementation instances are created by a ConstraintValidatorFactory
.
The lifecycle of ConstraintValidator
instances is fully dependent of the Bean Validation provider and piloted by the ConstraintValidatorFactory
methods. Therefore, ConstraintValidatorFactory
implementations (such as dependency injection frameworks) must consider these instances as belonging to a dependent scope. Bean Validation providers must release each instance retrieved. The ConstraintValidatorFactory
instance that has created a ConstraintValidator
instance must be the one that releases it. In other words, passing an instance of ConstraintValidator
to a ConstraintValidatorFactory
that has not created it is an error.
Note
|
|
ConstraintValidatorFactory
interface/**
* Instantiates a {@link ConstraintValidator} instance based off its class.
* The {@code ConstraintValidatorFactory} is <b>not</b> responsible
* for calling {@link ConstraintValidator#initialize(java.lang.annotation.Annotation)}.
*
* @author Dhanji R. Prasanna
* @author Emmanuel Bernard
* @author Hardy Ferentschik
*/
public interface ConstraintValidatorFactory {
/**
* @param key The class of the constraint validator to instantiate
* @param <T> The type of the constraint validator to instantiate
*
* @return A new constraint validator instance of the specified class
*/
<T extends ConstraintValidator<?, ?>> T getInstance(Class<T> key);
/**
* Signals {@code ConstraintValidatorFactory} that the instance is no longer
* being used by the Bean Validation provider.
*
* @param instance validator being released
*
* @since 1.1
*/
void releaseInstance(ConstraintValidator<?, ?> instance);
}
The default ConstraintValidatorFactory
provided by the Bean Validation provider implementation uses the public no-arg constructor of the ConstraintValidator
class. A custom ConstraintValidatorFactory
can be provided; for example it may benefit from dependency injection control in constraint implementations (see Bootstrapping considerations). Any constraint implementation relying on ConstraintValidatorFactory
behaviors specific to an implementation (dependency injection, no no-arg constructor and so on) is not portable, hence great care should be given before walking that path. Make sure to configure the Bean Validation provider to honor any specific needs your ConstraintValidator
has. As constraint designer and writer, make sure to document any specific non compliant requirements.
ConstraintValidatorFactory
should not cache instances as the state of each instance can be altered in the initialize()
method.
If an exception occurs in the factory while retrieving the ConstraintValidator
instance, the runtime exception is wrapped in a ValidationException
. If the instance returned by the factory is null, a ValidationException
is raised.
4. Value extractor definition
Validation of container element constraints (see Container element constraints) as well as cascaded validation of generic container types (see Graph validation) requires access to the value(s) stored in the container.
The retrieval of values stored in a container is handled via implementations of the ValueExtractor
interface:
ValueExtractor
interfacepackage javax.validation.valueextraction;
/**
* Defines the logic used to extract the values from a container object of type {@code T}.
* <p>
* A value extractor for a generic type such as {@link Optional}, {@link List} or {@link Map}
* is tied to one specific type parameter of {@code T}. The {@link ExtractedValue} annotation
* is used to mark that type parameter. A value extractor for a non-generic type such as
* {@link OptionalInt} needs to declare the type of the wrapped element(s) using
* {@link ExtractedValue#type()}.
* <p>
* The extracted values are passed to the corresponding method of the {@link ValueReceiver}.
* <p>
* A typical value extractor implementation for {@code List} may look like this:
*
* <pre>
* public class ListValueExtractor implements
* ValueExtractor<List<@ExtractedValue ?>> {
*
* @Override
* public void extractValues(List<?> originalValue, ValueReceiver receiver) {
* for ( int i = 0; i < originalValue.size(); i++ ) {
* receiver.indexedValue( "<list element>", i, originalValue.get( i ) );
* }
* }
* }
* </pre>
*
* @param <T> the container type handled by a specific implementation
*
* @author Gunnar Morling
* @author Guillaume Smet
* @see ExtractedValue
* @see UnwrapByDefault
* @since 2.0
*/
public interface ValueExtractor<T> {
/**
* Extracts the values to validate from the original object.
*
* @param originalValue the original value from which to extract the values, never
* {@code null}
* @param receiver the corresponding {@code ValueReceiver}
*/
void extractValues(T originalValue, ValueReceiver receiver);
/**
* Provides a set of methods receiving value extracted by the {@link ValueExtractor}.
* <p>
* The value has to be passed to the method corresponding best to the type of the
* original value.
*
* @since 2.0
*/
interface ValueReceiver {
/**
* Receives the value extracted from an object.
*
* @param nodeName the name of the node representing the container element. If not
* {@code null}, the name will be used when adding a container element node to the
* {@link Path}
* @param object the value to validate
*/
void value(String nodeName, Object object);
/**
* Receives the value extracted from an iterable object that is not indexed (e.g.
* a {@link Iterable}, {@link Set} or a {@link Map}).
*
* @param nodeName the name of the node representing the container element. If not
* {@code null}, the name will be used when adding a container element node to the
* {@link Path}
* @param object the value to validate
*/
void iterableValue(String nodeName, Object object);
/**
* Receives the value extracted from an indexed object (e.g. a {@link List}).
*
* @param nodeName the name of the node representing the container element. If not
* {@code null}, the name will be used when adding a container element node to the
* {@link Path}
* @param i the index of the value in the original object
* @param object the value to validate
*/
void indexedValue(String nodeName, int i, Object object);
/**
* Receives the value extracted from a keyed object (e.g. a {@link Map}).
*
* @param nodeName the name of the node representing the container element. If not
* {@code null}, the name will be used when adding a container element node to the
* {@link Path}
* @param key the key of the value in the original object
* @param object the value to validate
*/
void keyedValue(String nodeName, Object key, Object object);
}
}
The validation engine passes the container instance and a value receiver object to the extractValues()
method.
The value extractor is only invoked if the container is not null
.
Value extractor implementations must invoke one of the ValueReceiver
methods for each element contained in the container, passing the element value and, optionally, a node name.
When calling
-
value()
, the given value will be passed to the validation engine; -
iterableValue()
, the given value will be passed to the validation engine and the corresponding property path node (see ConstraintViolation) will be marked as iterable, i.e.Node#isInIterable()
returnstrue
; -
indexedValue()
, the given value will be passed to the validation engine and the corresponding property path node will be marked as iterable and it will have set the given index, i.e.Node#getIndex()
returns the given index value; -
keyedValue()
, the given value will be passed to the validation engine and the corresponding property path node will be marked as iterable and it will have set the given key, i.e.Node#getKey()
returns the given key value.
When passing a non-null node name to any of the receiver methods, this node name will be used when adding a node of kind CONTAINER_ELEMENT
to the property path (see ConstraintViolation for the property path construction rules).
If null is passed as node name, no node will be appended to the property path.
The resulting property path will then be the same as if the constraint had been given on the container instead of a container element.
That is desirable for single-element wrapper types such as Optional
, OptionalInt
etc.
If an exception occurs during invocation of the extractValues()
method, this exception is wrapped into a ValidationException
by the Bean Validation engine.
The container value passed to a value extractor is retrieved from the element that hosts the type argument carrying the constraint or @Valid
annotation:
public class Orders {
private Map<String, @Valid @RetailOrder Order> ordersByName;
public Map<@NotNull String, Order> getOrdersByName() {
return ordersByName;
}
[...]
}
When validating the @NotNull
constraint, the map as returned by the getter will be passed to the map key extractor in order to obtain the map keys.
When validating the @RetailOrder
constraint and performing cascaded validation,
the map as obtained directly from the field will be passed to the map value extractor in order to obtain the map values.
4.1. @ExtractedValue
The @ExtractedValue
annotation is used to denote the element extracted by a given value extractor:
@ExtractedValue
annotationpackage javax.validation.valueextraction;
/**
* Marks the type parameter of a generic container type to which a {@link ValueExtractor} is
* tied or specifies the type of the wrapped element(s) of non-generic container types.
* <p>
* Must be given exactly once for a value extractor type.
*
* @author Gunnar Morling
* @author Guillaume Smet
*
* @see ValueExtractor
* @since 2.0
*/
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE_USE)
@Documented
public @interface ExtractedValue {
/**
* The type of the value extracted by the {@link ValueExtractor}. If not set, the type
* will be automatically inferred from the type argument of the parameterized type.
* <p>
* Used to define value extractors for non-generic wrapper types e.g.
* {@link OptionalInt}.
* <p>
* May not be used when {@code ExtractedValue} is defined on the type parameter of
* a generic container type. A {@code ValueExtractorDefinitionException} will be thrown
* in this case.
*
* @return the type of the value extracted by the value extractor
*/
Class<?> type() default void.class;
}
The @ExtractedValue
annotation must be specified exactly once for a value extractor type.
For generic container types (e.g. java.util.List
), @ExtractedValue
is to be specified on a type argument of the container type as used in the extractor definition.
Only unbounded wildcard type arguments are supported as target for @ExtractedValue
in this case.
Note
|
This implies that only one extractor is supported for a given generic type.
I.e. there can be an extractor for |
For non-generic container types (e.g. java.util.OptionalInt
), @ExtractedValue
is to be specified on the container type as used in the extractor definition.
The type of the wrapped element(s) must be specified using @ExtractedValue#type()
in this case.
In case an illegal value extractor definition is detected, a ValueExtractorDefinitionException
is raised.
4.2. @UnwrapByDefault
Value extractor definitions can be marked with the @UnwrapByDefault
annotation.
This causes constraints to be automatically applied to the wrapped value(s) if a constraint is found for an element of a type handled by that extractor (see Implicit unwrapping of containers):
@UnwrapByDefault
annotationpackage javax.validation.valueextraction;
/**
* Marks a {@link ValueExtractor} definition so that it is applied automatically when
* detecting constraints declared on the container type supported by the extractor, causing
* the constraints to be applied to the container's elements instead of the container.
* <p>
* If needed, this behavior can be changed per constraint using {@link Unwrapping.Skip},
* causing the constraints to be applied to the container itself:
*
* <pre>
* @SomeConstraint(payload = Unwrapping.Skip.class)
* SomeContainerType container;
* </pre>
*
* @author Guillaume Smet
* @since 2.0
*/
@Target({ TYPE })
@Retention(RUNTIME)
@Documented
public @interface UnwrapByDefault {
}
4.3. Built-in value extractors
Compatible implementations provide value extractors for the following types out of the box:
-
java.util.Iterable
;iterableValue()
must be invoked for each contained element, passing the string literal<iterable element>
as node name -
java.util.List
;indexedValue()
must be invoked for each contained element, passing the string literal<list element>
as node name -
java.util.Map
; both map keys and map values are to be supported;keyedValue()
must be invoked by the map key extractor for each contained key, passing the string literal<map key>
as node name;keyedValue()
must be invoked by the map value extractor for each contained value, passing the string literal<map value>
as node name -
java.util.Optional
;value()
must be invoked, passingnull
as node name and passing the contained object as value ornull
if none is present -
java.util.OptionalInt
,java.util.OptionalLong
andjava.util.OptionalDouble
; the extracted value types must bejava.lang.Integer
,java.lang.Long
andjava.lang.Double
, respectively.value()
must be invoked, passingnull
as node name and passing the contained number as value ornull
if none is present. The extractors must be marked with@UnwrapByDefault
.
In environments where JavaFX is present, compatible implementations additionally provide extractors for the following types out of the box:
-
javafx.beans.observable.ObservableValue
;value()
must be invoked with the observable value, passingnull
as node name; the extractor must be marked with@UnwrapByDefault
-
javafx.beans.property.ReadOnlyListProperty
andjavafx.beans.property.ListProperty
;indexedValue()
must be invoked for each contained element, passing the string literal<list element>
as node name -
javafx.beans.property.ReadOnlySetProperty
andjavafx.beans.property.SetProperty
;iterableValue()
must be invoked for each contained element, passing the string literal<iterable element>
as node name -
javafx.beans.property.ReadOnlyMapProperty
andjavafx.beans.property.MapProperty
; both map keys and map values are to be supported;keyedValue()
must be invoked by the map key extractor for each contained key, passing the string literal<map key>
as node name;keyedValue()
must be invoked by the map value extractor for each contained value, passing the string literal<map value>
as node name
Additional value extractors (amending or overriding the set of built-in extractors) can be registered when bootstrapping the validation engine (see Registering ValueExtractor implementations).
4.4. Examples
A value extractor for the elements of java.util.List
:
class ListValueExtractor implements ValueExtractor<List<@ExtractedValue ?>> {
@Override
public void extractValues(List<?> originalValue, ValueReceiver receiver) {
for ( int i = 0; i < originalValue.size(); i++ ) {
receiver.indexedValue( "<list element>", i, originalValue.get( i ) );
}
}
}
This extractor passes each element contained in the given list to the receiver object,
using the literal <list element>
as a node name.
A value extractor for java.util.Optional
:
public class OptionalValueExtractor implements ValueExtractor<Optional<@ExtractedValue ?>> {
@Override
public void extractValues(Optional<?> originalValue, ValueReceiver receiver) {
receiver.value( null, originalValue.orElse( null ) );
}
}
This extractor passes the element wrapped by the given Optional
to the receiver object, if present.
null
is passed as a node name, causing no node to be appended to the resulting property path.
I.e. when the @Size
constraint in Optional<@Size(min=1) String getName() { … }
is violated,
the resulting property path will be the same as if a constraint hosted on the getName
getter itself was violated.
A value extractor for java.util.OptionalInt
:
@UnwrapByDefault
public class OptionalIntValueExtractor implements ValueExtractor<@ExtractedValue(type = Integer.class) OptionalInt> {
@Override
public void extractValues(OptionalInt originalValue, ValueReceiver receiver) {
receiver.value( null, originalValue.isPresent() ? originalValue.getAsInt() : null );
}
}
This extractor passes the int
value wrapped by the given OptionalInt
to the receiver object, if present.
null
is passed as a node name, causing no node to be appended to the resulting property path.
As the extractor is marked with @UnwrapByDefault
,
any constraint declared on an element of type OptionalInt
will implicitly be applied to the wrapped int
value instead of the OptionalInt
itself.
As OptionalInt
is a non-generic type (i.e. it has no type parameters), @ExtractedValue
is given on the container type as used within the value extractor definition,
specifying the type of the wrapped element via type()
.
The following extractor definition is illegal as it specifies @ExtractedValue
more than once:
public class IllegalMapExtractor implements ValueExtractor<Map<@ExtractedValue ?, @ExtractedValue ?>> { ... }
The following extractor definition is unsupported as it specifies @ExtractedValue
on a non-wildcard type argument:
public class StringListValueExtractor implements ValueExtractor<List<@ExtractedValue String>> { ... }
5. Constraint declaration and validation process
The Bean Validation specification defines a framework for declaring constraints on JavaBean classes, fields and properties. Constraints are declared on types and evaluated against instances or graphs of instances.
Bean Validation also offers a way to declare constructor and method constraints where parameters and return values are the constrained elements. We will discuss method constraints declaration in detail in Method and constructor constraints.
Furthermore, constraints can be applied to the elements of generic container types such as Map
, List
or Optional
or of non-generic container types such as OptionalInt
.
Container element constraints are discussed in detail in Container element constraints.
5.1. Requirements on classes to be validated
Objects hosting constraints and expecting to be validated by Bean Validation providers must fulfill the following requirements:
-
Properties to be validated must follow the method signature conventions for JavaBeans read properties, as defined by the JavaBeans specification. These properties are commonly referred as getters.
-
Static fields and static methods are excluded from validation.
-
Constraints can be applied to interfaces and superclasses.
Note
|
What is a getter?
The JavaBeans specification specifies that a getter is a method whose
|
The target of an annotation definition can be a
-
type
-
field or property
-
constructor or method return value
-
constructor or method parameter
-
constructor or method cross-parameter
-
container element
provided that:
-
the constraint definition supports the specified target (
java.lang.annotation.Target
) -
one of the
ConstraintValidator
s declared on the constraint supports the declared type of the target or in the case of cross-parameter, one cross-parameterConstraintValidator
is present (see ConstraintValidator resolution algorithm to learn aboutConstraintValidator
resolution) -
in the case of container element constraints, a corresponding value extractor exists (see ValueExtractor resolution for the details of value extractor resolution)
5.1.1. Object validation
Constraint declarations can be applied to a class or an interface. Applying a constraint to a class or interface expresses a validation over the state of the class or the class implementing the interface.
5.1.2. Field and property validation
Constraint declarations can be applied on both fields and properties for the same object type. The same constraint should however not be duplicated between a field and its associated property (the constraint validation would be applied twice). It is recommended for objects holding constraint declarations to adhere to a single state access strategy (either annotated fields or properties).
Note
|
Java Persistence and Bean Validation
For maximum portability, persistent properties hosting Bean Validation constraints should use the same access strategy used in Java Persistence. In other words, place your Bean Validation constraint annotations on the same element (field or getter) as your Java Persistence annotations. |
When a field is annotated with a constraint declaration, field access strategy is used to access the state validated by such constraint.
When a property is annotated with a constraint declaration, property access strategy is used to access the state validated by such constraint.
When using field access strategy, the Bean Validation provider accesses the instance variable directly. When using the property access strategy, the Bean Validation provider accesses the state via the property accessor method. It is required that the class follows the method signature conventions for JavaBeans read properties (as defined by the JavaBeans Introspector
class) for constrained properties when constrained properties are used. In this case, for every constraint property of type T
, there is a getter method named get<Property-name>
. The method must have no parameters. For boolean
properties, is<Property-name>
is an alternative name for the getter method. Specifically, if getX
is the name of the getter method, where X
is a string, the name of the persistent property is defined by the result of java.beans.Introspector.decapitalize(X)
.
The fields or methods visibility are not constrained.
5.1.3. Graph validation
In addition to supporting instance validation, validation of graphs of objects is also supported. The result of a graph validation is returned as a unified set of constraint violations. @Valid
is used to express validation traversal of an association.
@Valid
annotation/**
* Marks a property, method parameter or method return type for validation cascading.
* <p>
* Constraints defined on the object and its properties are be validated when the
* property, method parameter or method return type is validated.
* <p>
* This behavior is applied recursively.
*
* @author Emmanuel Bernard
* @author Hardy Ferentschik
*/
@Target({ METHOD, FIELD, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
public @interface Valid {
}
Consider the situation where bean X
contains a field of type Y
. By annotating field Y
with the @Valid
annotation, the Validator will validate Y
(and its properties) when X
is validated. The exact type Z
of the value contained in the field declared of type Y
(subclass, implementation) is determined at runtime. The constraint definitions of Z
are used. This ensures proper polymorphic behavior for associations marked with @Valid
.
Collection-valued, array-valued and generally Iterable
fields and properties may also be decorated with the @Valid
annotation. This causes the contents of the iterator to be validated. Any object implementing java.lang.Iterable
is supported. This includes specifically:
-
arrays of objects
-
java.util.Collection
-
java.util.Set
-
java.util.List
-
java.util.Map
(special treatment see below)
Each object provided by the iterator is validated. For Map
, the value (retrieved by getValue
) of each Map.Entry
is validated (the key is not validated).
Like regular references, its type is determined at runtime and the constraint definitions for this particular type are used.
As of Bean Validation 2.0, @Valid
can be applied to the elements of any generic container by putting it to the type argument(s) when using such container (e.g. MultiMap<String, @Valid Address> addressesByType
),
provided a value extractor implementation (see Value extractor definition) for that container type and the targeted type argument is present.
There are built-in value extractors for the generic collection types listed above.
In addition, there is a built-in extractor for the key objects of maps.
See Built-in value extractors for the complete list of built-in value extractors.
@Valid
also allows the validation of the elements of nested generic containers. @Valid
must be put to a type argument of that nested container type in order to trigger validation of the elements of all the nested containers.
For a given container, the @Valid
annotation should either be put to the container itself or to the type argument(s) of the container,
but not both (in order to prevent the container elements from being validated twice).
The @Valid
annotation is applied recursively. A conforming implementation avoids infinite loops according to the rules described in Object graph validation.
It is not supported to put @Valid
to the type parameters of generic types or methods.
It is also not supported to put @Valid
to type arguments within the extends
or implements
clauses of type definitions.
A future revision of this specification might define support for such usages of @Valid
.
5.1.3.1. Examples
public class User {
// preferred style as of Bean Validation 2.0
private List<@Valid PhoneNumber> phoneNumbers;
// traditional style; continues to be supported
@Valid
private List<PhoneNumber> phoneNumbers;
// discouraged; either the container or the type argument(s) should be
// annotated with @Valid, but not both
@Valid
private List<@Valid PhoneNumber> phoneNumbers;
}
public class User {
// preferred style as of Bean Validation 2.0
private Map<AddressType, @Valid Address> addressesByType;
// traditional style; continues to be supported
@Valid
private Map<AddressType, Address> addressesByType;
// discouraged; either the map or the map value type argument should be
// annotated with @Valid, but not both
@Valid
private Map<AddressType, @Valid Address> addressesByType;
}
public class User {
private Map<@Valid AddressType, @Valid Address> addressesByType;
}
public class User {
private Map<String, List<@Valid Address>> addressesByType;
}
In this example, all Address
objects contained in the lists of the addressesByType
map will be validated.
Two value extractors are invoked for this:
-
the extractor for
Map
values will be invoked to obtain all map values (lists ofAddress
) -
for each extracted list of addresses, the extractor for
List
elements will be invoked, providing theAddress
objects from each list in the map
public class User {
private Map<String, Map<@Valid AddressType, @Valid Address>> addressesByUserAndType;
}
In this example, all AddressType
objects and all Address
objects contained in the maps of the addressesByUserAndType
map will be validated.
The following value extractors are invoked for this:
-
the extractor for
Map
values will be invoked to obtain all map values (maps of addresses by address type) -
for each extracted map, the extractor for
Map
keys will be invoked, providing theAddressType
objects from each of the nested maps -
for each extracted map, the extractor for
Map
values will be invoked, providing theAddress
objects from each of the nested maps
5.2. Constraint declaration
Constraint declarations are placed on classes or interfaces primarily through annotations. A constraint annotation (see Constraint annotation), can be applied to a type, on any of the type’s fields or on any of the JavaBeans-compliant properties.
When a constraint is defined on a class, the class instance being validated is passed to the ConstraintValidator
. When a constraint is defined on a field, the value of the field is passed to the ConstraintValidator
. When a constraint is defined on a getter, the result of the getter invocation is passed to the ConstraintValidator
.
Method and constructor constraints discusses in detail constraints on methods and constructors.
Constraints can also be applied to the elements of container types, e.g. to the elements of a List
-typed property or to the value wrapped by an Optional
object returned by a method.
Container element constraints are discussed in Container element constraints.
5.3. Inheritance (interface and superclass)
A constraint declaration can be placed on an interface. For a given class, constraint declarations held on superclasses as well as interfaces are evaluated by the Bean Validation provider. Rules are formally described in Formal group definitions.
The effect of constraint declarations is cumulative. Constraints declared on a superclass getter will be validated along with any constraints defined on an overridden version of the getter according to the Java Language Specification visibility rules.
5.4. Group and group sequence
A group defines a subset of constraints. Instead of validating all constraints for a given object graph, only a subset is validated. This subset is defined by the group or groups targeted. Each constraint declaration defines the list of groups it belongs to. If no group is explicitly declared, a constraint belongs to the Default
group.
Groups are represented by interfaces.
/**
* Validation group verifing that a user is billable
*/
public interface Billable {}
/**
* Customer can buy without any harrassing checking process
*/
public interface BuyInOneClick {
}
A constraint can belong to one or more groups.
/**
* User representation
*/
public class User {
@NotNull
private String firstname;
@NotNull(groups = Default.class)
private String lastname;
@NotNull(groups = {Billable.class, BuyInOneClick.class})
private CreditCard defaultCreditCard;
}
During the validation call, one or more groups are validated. All the constraints belonging to this set of groups is evaluated on the object graph. In Assign groups to constraints, @NotNull
is checked on defaultCreditCard
when either the Billable
or BuyInOneClick
group is validated. @NotNull
on firstname
and lastname
are validated when the Default
group is validated. Reminder: constraints held on superclasses and interfaces are considered.
Default
is a group predefined by the specification.
Default
grouppackage javax.validation.groups;
/**
* Default Bean Validation group.
* <p>
* Unless a list of groups is explicitly defined:
* <ul>
* <li>constraints belong to the {@code Default} group</li>
* <li>validation applies to the {@code Default} group</li>
* </ul>
* Most structural constraints should belong to the default group.
*
* @author Emmanuel Bernard
*/
public interface Default {
}
5.4.1. Group inheritance
In some situations, a group is a superset of one or more groups. This can be described by Bean Validation. A group may inherit one or more groups by using interface inheritance.
/**
* Customer can buy without harrassing checking process
*/
public interface BuyInOneClick extends Default, Billable {}
For a given interface Z
, constraints marked as belonging to the group Z
(i.e. where the annotation element groups
contains the interface Z
) or any of the super interfaces of Z
(inherited groups) are considered part of the group Z
.
In the following example:
/**
* User representation
*/
public class User {
@NotNull
private String firstname;
@NotNull(groups = Default.class)
private String lastname;
@NotNull(groups = Billable.class)
private CreditCard defaultCreditCard;
}
validating the group BuyInOneClick
will lead to the following constraints checking:
-
@NotNull
onfirstname
andlastname
-
@NotNull
ondefaultCreditCard
because Default
and Billable
are superinterfaces of BuyInOneClick
.
5.4.2. Group sequence
By default, constraints are evaluated in no particular order regardless of which groups they belong to. It is however useful in some situations to control the order of constraints evaluation. There are often scenarios where a preliminary set of constraints should be evaluated prior to other constraints. Here are two examples:
-
The second group depends on a stable state to run properly. This stable state is verified by the first group.
-
The second group is a heavy consumer of time, CPU or memory and its evaluation should be avoided if possible.
To implement such ordering, a group can be defined as a sequence of other groups. Each group in a group sequence must be processed sequentially in the order defined by @GroupSequence.value
when the group defined as a sequence is requested. Note that a group member of a sequence can itself be composed of several groups via inheritance or sequence definition. In this case, each composed group must respect the sequence order as well.
Processing a group is defined in Validation routine ; if one of the groups processed in the sequence generates one or more constraint violations, the groups following in the sequence must not be processed. This ensures that a set of constraints is evaluated only if another set of constraints is valid.
Groups defining a sequence and groups composing a sequence must not be involved in a cyclic dependency:
-
either directly or indirectly
-
either through cascaded sequence definitions or group inheritance
If a group containing such a circularity is evaluated, a GroupDefinitionException
is raised.
Groups defining a sequence should not directly inherit other groups. In other words, the interface hosting the group sequence should not have any super interface.
Groups defining a sequence should not be used directly in constraint declarations. In other words, the interface hosting the group sequence should not be used in a constraint declaration.
To define a group as a sequence, the interface must be annotated with the @GroupSequence
annotation.
@GroupSequence
annotation/**
* Defines group sequence.
* <p>
* The interface hosting {@code @GroupSequence} is representing
* the group sequence.
* When hosted on a class, represents the {@link Default} group
* for that class.
*
* @author Emmanuel Bernard
* @author Hardy Ferentschik
*/
@Target({ TYPE })
@Retention(RUNTIME)
@Documented
public @interface GroupSequence {
Class<?>[] value();
}
Here is a usage example:
@ZipCodeCoherenceChecker(groups = Address.HighLevelCoherence.class)
public class Address {
@NotNull @Size(max = 50)
private String street1;
@NotNull @ZipCode
private String zipCode;
@NotNull @Size(max = 30)
private String city;
/**
* check coherence on the overall object
* Needs basic checking to be green first
*/
public interface HighLevelCoherence {}
/**
* check both basic constraints and high level ones.
* high level constraints are not checked if basic constraints fail
*/
@GroupSequence({Default.class, HighLevelCoherence.class})
public interface Complete {}
}
In Make use of group sequence, when the Address.Complete
group is validated, all constraints belonging to the Default
group are validated. If any of them fail, the validation skips the HighLevelCoherence
group. If all Default
constraints pass, HighLevelCoherence
constraints are evaluated.
Note
|
A given constraint can belong to two or more groups ordered by a sequence. In this case, the constraint is evaluated as part of the first group and ignored in the subsequent group(s). See Validation routine for more information. |
5.4.3. Redefining the Default group for a class
In Make use of group sequence, validating the Default
group does not validate HighLevelCoherence
constraints. To ensure a complete validation, a user must use the Complete
group. This breaks some of the encapsulation you could expect. You can work around this by redefining what the Default
group means for a given class. To redefine Default
for a class, place a @GroupSequence
annotation on the class; this sequence expresses the sequence of groups that does substitute Default
for this class.
@GroupSequence({Address.class, HighLevelCoherence.class})
@ZipCodeCoherenceChecker(groups = Address.HighLevelCoherence.class)
public class Address {
@NotNull @Size(max = 50)
private String street1;
@NotNull @ZipCode
private String zipCode;
@NotNull @Size(max = 30)
private String city;
/**
* check coherence on the overall object
* Needs basic checking to be green first
*/
public interface HighLevelCoherence {}
}
In Redefining Default group for Address, when an address object is validated for the group Default
, all constraints belonging to the group Default
and hosted on Address
are evaluated. If none fails, all HighLevelCoherence
constraints present on Address
are evaluated. In other words, when validating the Default
group for Address
, the group sequence defined on the Address
class is used.
Since sequences cannot have circular dependencies, using Default
in the declaration of a sequence is not an option. Constraints hosted on a class A
and belonging to the Default
group (by default or explicitly) implicitly belong to the group A
.
A sequence defined on a class A
(i.e. redefining the Default
groups for the class) must contain the group A
. In other words, the default constraints hosted on a class must be part of the sequence definition. If a @GroupSequence
redefining the Default
group for a class A
does not contain the group A
, a GroupDefinitionException
is raised when the class is validated or when its metadata is requested.
5.4.4. Implicit grouping
It is possible to implicitly group several constraints in the same group without explicitly listing such a group in the constraint declaration. Every constraint hosted on an interface Z
and part of the Default
group (implicitly or explicitly) belongs to the group Z
. This is useful to validate the partial state of an object based on a role represented by an interface.
/**
* Auditable object contract
*/
public interface Auditable {
@NotNull String getCreationDate();
@NotNull String getLastUpdate();
@NotNull String getLastModifier();
@NotNull String getLastReader();
}
/**
* Represents an order in the system
*/
public class Order implements Auditable {
private String creationDate;
private String lastUpdate;
private String lastModifier;
private String lastReader;
private String orderNumber;
public String getCreationDate() {
return this.creationDate;
}
public String getLastUpdate() {
return this.lastUpdate;
}
public String getLastModifier() {
return this.lastModifier;
}
public String getLastReader() {
return this.lastReader;
}
@NotNull @Size(min=10, max=10)
public String getOrderNumber() {
return this.orderNumber;
}
}
When an Order
object is validated on the Default
group, the following constraints are validated: @NotNull
on getCreationDate
, getLastUpdate
, getLastModifier
, getLastReader
, getOrderNumber
and @Size
on getOrderNumber
as all belong to the Default
group.
When an Order
object is validated on the Auditable
group, the following constraints are validated: @NotNull
on getCreationDate
, getLastUpdate
, getLastModifier
, getLastReader
. Only the constraints present on Auditable
(and any of its super interfaces) and belonging to the Default
group are validated when the group Auditable
is requested. It allows the caller to validate that a given object can be safely audited even if the object state itself is not valid.
5.4.5. Group conversion
When performing cascading validation, it is possible to use a different group than the one originally requested using the group conversion feature. Group conversions are declared by using the @ConvertGroup
annotation.
package javax.validation.groups;
/**
* Converts group {@code from} to group {@code to} during cascading.
* <p>
* Can be used everywhere {@link Valid} is used and must be on an element
* annotated with {@code Valid}.
*
* @author Emmanuel Bernard
* @since 1.1
*/
@Target({ METHOD, FIELD, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
@Documented
public @interface ConvertGroup {
/**
* The source group of this conversion.
* @return the source group of this conversion
*/
Class<?> from() default Default.class;
/**
* The target group of this conversion.
* @return the target group of this conversion
*/
Class<?> to();
/**
* Defines several {@link ConvertGroup} annotations
* on the same element.
*/
@Target({ METHOD, FIELD, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
public @interface List {
ConvertGroup[] value();
}
}
@ConvertGroup
and @ConvertGroup.List
can be used everywhere @Valid
can be used (associations, method/constructor parameters and return value). If these annotations are used without @Valid
, a ConstraintDeclarationException
is raised.
When an element is annotated with @Valid
, validation is propagated. Groups are passed as is to the nested elements unless the @ConvertGroup
annotation is used.
If the group expected to be passed to the nested element validation is defined as the from
attribute of a @ConvertGroup
annotation, the group used to effectively validate the nested element is the corresponding group defined in the to
attribute.
If no value for the from
attribute is specified, Default.class
will be used as the source group of the conversion.
Rules are not executed recursively. If a rule is found matching, subsequent rules are no longer evaluated. In particular, if a set of @ConvertGroup
declaration chains group A
to B
and B
to C
, the group A
will be converted to B
and not to C
. This both makes rules clearer and let you switch two groups.
It is not legal to have more than one conversion rule containing the same from
value. In this case, a ConstraintDeclarationException
is raised.
Like regular constraint declarations, the from
attribute cannot refer to a group sequence. A ConstraintDeclarationException
is raised in this situation. The to
attribute can. The group sequence will then be expanded before validating the associated object.
Note
|
When validation is done, group sequences are expanded before validating the object and its cascaded objects with the expected groups. Group conversion on an associated object happens on the already expanded groups. The group referred to in The group referred to in |
Note
|
Like most Bean Validation error cases, an illegal set of rules can be discovered statically (at compile time). For example, an annotation processor could detect such errors. |
Note
|
Group circularity in a group conversion are not problematic because:
|
@ConvertGroup
and @ConvertGroup.List
can only be placed where @Valid
is present to ensure proper respect of the Liskov substitution principle: if rules were to be defined on an overriding method of a method marked as cascading validation, the rules could end up altering the list of constraints validated by the super type and thus violating the Liskov substitution principle.
Likewise, if a sub type overrides/implements a method originally defined in several parallel types of the hierarchy (e.g. two interfaces not extending each other, or a class and an interface not implemented by said class) and if that method’s return value has been marked for cascading validation in one of the parallel types, no group conversion rule may be declared for that method’s return value in the parallel types of the hierarchy. This again is to avoid an unexpected altering of the post conditions to be guaranteed to the caller.
If any of these rules is violated, a ConstraintDeclarationException
is raised by default as defined in Method constraints in inheritance hierarchies.
Group conversion is quite useful to facilitate object graph reuse without spreading the validation group definitions across several layers. Let’s look at an example.
5.4.5.1. Group conversion examples
In this example we will reuse the Address
group split and match it to the User
group split.
public interface Complete extends Default {}
public interface BasicPostal {}
public interface FullPostal extends BasicPostal {}
public class Address {
@NotNull(groups=BasicPostal.class)
String street1;
String street2;
@ZipCode(groups=BasicPostal.class)
String zipCode;
@CodeChecker(groups=FullPostal.class)
String doorCode;
}
public class User {
@Valid
@ConvertGroup(from=Default.class, to=BasicPostal.class)
@ConvertGroup(from=Complete.class, to=FullPostal.class)
Set<Address> getAddresses() { [...] }
}
When validating an instance of User
with the Default
group, the associated addresses are validated with the BasicPostal
group. When validating an instance of User
with the Complete
group, the associated addresses are validated with the FullPostal
group.
Group conversions can also be applied during container element validation:
public class User {
Set<
@Valid
@ConvertGroup(from=Default.class, to=BasicPostal.class)
@ConvertGroup(from=Complete.class, to=FullPostal.class)
Address
> getAddresses() { [...] }
}
The following example shows an illegal declaration of a group conversion rule on a method’s return value:
public interface BasicPostal {}
public class Order { [...] }
public interface RetailOrderService {
@Valid
Order placeOrder(String itemNo, int quantity);
}
public interface B2BOrderService {
@Valid
@ConvertGroup(from=Default.class, to=BasicPostal.class)
Order placeOrder(String itemNo, int quantity);
}
public class OrderService implements RetailOrderService, B2BOrderService {
@Override
public Order placeOrder(String itemNo, int quantity) {
[...]
}
}
Here the class OrderService
implements the two unrelated interfaces RetailOrderService
and B2BOrderService
, which both define a method placeOrder()
, marking the return value as cascaded.
The group conversion declared in B2BOrderService
is illegal as per the rules defined in the previous section, since the set of applied validation groups might be altered unexpectedly for a client of the RetailOrderService
interface.
5.4.6. Formal group definitions
The formal rules defining groups are as followed. Text in italic are comments about the rules.
For every class X
:
-
For each superclass
Y
ofX
, the groupY
contains all constraints of the groupY
ofY
this rule prepares formal concepts for recursive discovery
-
The group
X
contains the following constraints: groupX
is a group used on sequences redefining the default group on a class (see Redefining the Default group for a class)-
every constraint declared by the class
X
which does not declare a group or does declare the groupDefault
explicitly. all Default constraints hosted on X -
every constraint declared by any interface implemented by
X
and not annotated@GroupSequence
which does not explicitly declare a group or does declare the groupDefault
explicitly. all Default constraints hosted on interfaces of X: constraints are inherited by the class hierarchy. Interfaces marked as @GroupSequence are ignored. -
if
X
has a direct superclassY
, every constraint in the groupY
all Default constraints hosted on the superclasses of X: constraints are inherited by the class hierarchy
-
-
If
X
has no@GroupSequence
annotation, the groupDefault
contains the following constraints: this rule defines which constraints are evaluated when validating Default on X.-
every constraint in the group
X
-
if
X
has a direct superclassY
, every constraint in the groupDefault
ofY
this rule is necessary in case Y redefines the group Default
-
-
If
X
does have a@GroupSequence
annotation, the groupDefault
contains every constraint belonging to every group declared by the@GroupSequence
annotation. this rule describes how a class can redefine the group Default for itself (see Redefining the Default group for a class)-
the
@GroupSequence
annotation must declare the groupX
-
-
For every interface
Z
, the groupZ
contains the following constraints: this rule defines how non Default groups are defined-
every constraint declared by the interface
Z
which does not explicitly declare a group or does declare the groupDefault
explicitly. all Default constraints hosted on Z: this rule formally defines implicit grouping per interface (see Implicit grouping) -
every constraint (which does not explicitly declare a group) declared by any superinterface not annotated
@GroupSequence
of the interfaceZ
all Default constraints hosted on interfaces of Z: groups can be inherited (see Group inheritance) -
every constraint declared by the class
X
which explicitly declares the groupZ
every constraint hosted by X and marked as belonging to the group Z -
every constraint declared by any interface implemented by
X
and not annotated@GroupSequence
which explicitly declares the groupZ
every constraint hosted by any interface of X and marked as belonging to the group Z -
if
X
has a direct superclassY
, every constraint in the groupZ
ofY
every constraint hosted by any superclass of X and marked as belonging to the group Z
-
-
For every interface
Z
annotated@GroupSequence
, the groupZ
contains every constraint belonging to every group declared by the@GroupSequence
annotation. defines the composition side of group sequence but does not define the ordering behavior of sequence (see Group sequence)
When a given group G
(represented by an interface G
) is requested for the validation of a class X
:
-
constraints belonging to the group
G
are evaluated -
if the interface
G
is not annotated@GroupSequence
, every group represented by the super interface ofG
are requested for validation -
if the interface
G
is annotated with@GroupSequence
, every group represented by the interfaces declared by the@GroupSequence
annotation are requested for validation-
the validation of groups declared to the
@GroupSequence
must happen in the sequencing order declared by@GroupSequence
: the sequencing order is propagated to the groups composing the sequenced group (via inheritance or group sequence) -
if a group validation triggers the failure of one or more constraints, groups following in the sequence must not be evaluated.
-
-
if the group
G
represents theDefault
group ofX
overridden by@GroupSequence
, operations are equivalent
When the Default
group of a given class X
is overridden via @GroupSequence
, its validation is as followed:
-
every group represented by the interfaces declared by the
@GroupSequence
annotation are requested for validation-
the validation of groups declared to the
@GroupSequence
must happen in the sequencing order declared by@GroupSequence
: the sequencing order is propagated to the groups composing the sequenced group (via inheritance or group sequence) -
if a group validation triggers the failure of one or more constraints, groups following in the sequence must not be evaluated.
-
Unless defined by a @GroupSequence
, evaluation ordering is not constrained. In particular, several groups can be validated in the same pass. If a group definition leads to a circular sequencing order between groups, a GroupDefinitionException
is raised.
Note
|
A group |
5.5. Container element constraints
Constraints can be applied to the elements of generic containers, e.g. List
, Map
or Optional
.
This is done by putting constraint annotations to the type arguments of such containers.
Container element constraints can be used within the following declarations:
-
fields,
-
properties,
-
method or constructor parameters or
-
method return values.
private List<@Email String> emails;
public Optional<@Email String> getEmail() {
[...]
}
public Map<@NotNull String, @ValidAddress Address> getAddressesByType() {
[...]
}
public List<@NotBlank String> getMatchingRecords(List<@NotNull @Size(max=20) String> searchTerms) {
[...]
}
When a field, property, executable parameter or method return value which is of a container type gets validated, then all values contained in the container will be validated provided that their container element type is constrained. Any container element constraints of that element will be validated alongside any other constraints hosted by that element. For container element constraints, the same rules for validation groups and group sequences apply as for any other constraint on the same element.
When a container element is constrained, the validation engine invokes a value extractor (see Value extractor definition)
which retrieves the value(s) from the container so they can be validated.
This may be a single value - e.g. in the case of Optional
which wraps exactly one value if the Optional
is not empty -
or multiple values in the case of collection types.
Container element constraints can be applied to nested container types:
private Map<String, @NotEmpty List<@ValidAddress Address>> addressesByType;
In such case multiple value extractors will be invoked.
In the example above,
-
the extractor for
Map
values will be invoked to obtain all map values (lists ofAddress
) -
for each extracted list of addresses, the
@NotEmpty
constraint will be validated and the extractor forList
elements will be invoked, providing theAddress
objects from each list in the map -
the
@ValidAddress
constraint will be applied to all elements of all lists stored in the map
It is not supported to declare container element constraints on the type parameters of generic types or methods.
It is also not supported to declare container element constraints on type arguments within the extends
or implements
clauses of type definitions.
I.e. the following usages are unsupported:
public class NonNullList<@NotNull T> {
[...]
}
public class ContainerFactory {
<@NotNull T> Container<T> instantiateContainer(T wrapped) { [...] }
}
public class NonNullSet<T> extends Set<@NotNull T> {
[...]
}
A future revision of this specification might define support for such usages of container element constraints.
5.5.1. Implicit unwrapping of containers
Besides specifying container element constraints on type arguments, it is also possible to declare container element constraints on non-generic container types.
This is done by means of implicit unwrapping, i.e. a constraint doesn’t apply to the annotated container itself but to its element(s).
Examples for types being subject to implicit unwrapping are java.util.OptionalInt
, OptionalLong
and OptionalDouble
as well as JavaFX’s non-generic property types such as StringProperty
or IntegerProperty
:
@Min(1)
private OptionalInt optionalNumber;
@Negative
private LongProperty negativeLong;
@Positive
private IntegerProperty positiveInt;
private final ListProperty<@NotBlank StringProperty> notBlankStrings;
Here the @Min
, @Negative
, @Positive
and @NotBlank
constraints don’t apply to the annotated OptionalInt
, LongProperty
, IntegerProperty
and StringProperty
objects themselves, but rather to the wrapped numeric and string values, respectively.
For this to work, an unambiguously resolvable value extractor (see ValueExtractor resolution algorithm for applying container-level constraints to container elements) must be defined which carries the @UnwrapByDefault
annotation (see @UnwrapByDefault).
If needed, the target (container or container element) of a constraint declared on a container can be explicitly specified via the Unwrap
and Skip
payload definitions:
Payload
types for unwrapping controlpackage javax.validation.valueextraction;
/**
* Set of interfaces used in the {@code payload()} of a constraint to indicate if a value
* should be unwrapped before validation.
* <p>
* This is used to overwrite the default configuration defined on the {@link ValueExtractor}.
*
* @author Guillaume Smet
* @since 2.0
*/
public interface Unwrapping {
/**
* Unwrap the value before validation.
*
* @since 2.0
*/
public interface Unwrap extends Payload {
}
/**
* Skip the unwrapping if it has been enabled on the {@link ValueExtractor} by the
* {@link UnwrapByDefault}
* annotation.
*
* @since 2.0
*/
public interface Skip extends Payload {
}
}
This is useful for applying a constraint given on a non-generic container to
-
the container element(s) if there is no value extractor marked with
@UnwrapByDefault
(by usingUnwrap
) -
the container itself in case there is a value extractor marked with
@UnwrapByDefault
(by usingSkip
)
For instance the @NotNull
constraint is applied to the StringProperty
container:
@NotNull(payload = Unwrapping.Skip.class)
private StringProperty name;
If both Unwrap
and Skip
are present in the definition of a payload, a ConstraintDeclarationException
is raised.
Note
|
For the sake of readability, when applying constraints to the elements of a generic container,
it is strongly recommended to put the constraints to the type argument instead of the container itself in conjunction with
over
|
5.6. Method and constructor constraints
Note
|
In the following, the term "method constraint" refers to constraints declared on methods as well as constructors. |
Method constraints are declared by adding constraint annotations directly to methods or constructors and/or their parameters. In the former case, all the parameters of an executable (cross-parameter constraint) or the return value is constrained, in the latter individual parameters are constrained. As with bean constraints, this can be done using either actual Java annotations or using an XML constraint mapping file (see Method-level overriding). Bean Validation providers are free to provide additional means of defining method constraints such as an API-based approach.
Getters are not considered constrained methods by default (see Method and constructor validation).
5.6.1. Requirements on methods to be validated
Static methods are ignored by validation. Putting constraints on a static method is not portable. No other restrictions exist from the perspective of this specification, however it is possible that technologies integrating with method validation impose further restrictions to methods for which a validation shall be applied. For instance certain integration technologies might require that methods to be validated must have public
visibility and/or must not be final
.
5.6.2. Declaring parameter constraints
Parameter constraints are declared by putting constraint annotations on method or constructor parameters.
public class OrderService {
public OrderService(@NotNull CreditCardProcessor creditCardProcessor) {
[...]
}
public void placeOrder(
@NotNull @Size(min=3, max=20) String customerCode,
@NotNull Item item,
@Min(1) int quantity) {
[...]
}
}
Using constraint annotations, several preconditions are defined here. These preconditions which must be satisfied in order to legally invoke the methods of OrderService
are:
-
The
CreditCardProcessor
passed to the constructor must not be null. -
The customer code passed to the
placeOrder()
method must not be null and must be between 3 and 20 characters long. -
The
Item
passed to theplaceOrder()
method must not be null. -
The quantity value passed to the
placeOrder()
method must be 1 at least.
Note that declaring these constraints does not automatically cause their validation when the concerned methods are invoked. It’s the responsibility of an integration layer to trigger the validation of the constraints using a method interceptor, dynamic proxy or similar. See section Triggering method validation for more details.
Tip
|
In order to use constraint annotations for method or constructor parameters, their element type must be |
5.6.2.1. Cross-parameter constraints
Cross-parameter constraints allow to express constraints based on the value of several method parameters, similar to class-level constraints which are based on several properties of a given class. Cross-parameter constraints are declared by putting cross-parameter constraint annotations on methods or constructors as shown in the following example.
public class CalendarService {
@ConsistentDateParameters
public void createEvent(
String title,
@NotNull Date startDate,
@NotNull Date endDate) {
[...]
}
}
The cross-parameter constraint annotation expresses here that the given start date must be before the passed end date in order to legally invoke the createEvent()
method. The example also shows that it is often useful to combine constraints directly placed on individual parameters (e.g. @NotNull
) and cross-parameter constraints.
Tip
|
Cross-parameter constraints as well as return value constraints are declared directly on a method or a constructor. To make it obvious for a reader that an annotation refers to the parameters of a method or constructor and not its return value, it is recommended to choose a name which clearly expresses this intention. |
It is not legal to declare a cross-parameter constraint on a method or constructor which has no parameters. A ConstraintDeclarationException
is raised in this case.
Some constraints can target an executable’s return value as well as its array of parameters. They are known to be both generic and cross-parameter constraints. When using such a constraint on an executable to target the parameters, one must set validationAppliesTo
if there is an ambiguity. The set of ambiguities is described in validationAppliesTo. Even without ambiguity, it is recommended to explicitly set validationAppliesTo
to ConstraintTarget.PARAMETERS
as it improves readability.
5.6.2.2. Naming parameters
In case the validation of a parameter constraint fails, the concerned parameter needs to be identified in the resulting ConstraintViolation
(see section ConstraintViolation). Bean Validation defines the javax.validation.ParameterNameProvider
API to which the retrieval of parameter names is delegated:
ParameterNameProvider
interface/**
* Provides names for method and constructor parameters.
* <p>
* Used by the Bean Validation runtime when creating constraint violation
* objects for violated method constraints.
* <p>
* Implementations must be thread-safe.
*
* @author Gunnar Morling
* @since 1.1
*/
public interface ParameterNameProvider {
/**
* Returns the names of the parameters of the given constructor.
*
* @param constructor the constructor for which the parameter names shall be
* retrieved; never {@code null}
* @return a list containing the names of the parameters of the given
* constructor; may be empty but never {@code null}
*/
List<String> getParameterNames(Constructor<?> constructor);
/**
* Returns the names of the parameters of the given method.
*
* @param method the method for which the parameter names shall be retrieved;
* never {@code null}
* @return a list containing the names of the parameters of the given method;
* may be empty but never {@code null}
*/
List<String> getParameterNames(Method method);
}
A conforming Bean Validation implementation provides a default ParameterNameProvider
implementation which returns parameter names as stored in the class file containing the validated executable, if present. A conforming implementation must either use the Java reflection API or ensure behavioral compatibility to using the reflection API in the following way:
-
Obtain the method’s or constructor’s parameters via
java.lang.reflect.Executable.getParameters()
-
Obtain each parameter’s name via
java.lang.reflect.Parameter.getName()
Depending on whether the class file of the validated executable contains parameter name information or not, the actual parameter names as provided in the executable’s definition will be returned or synthetic names in the form argPARAMETER_INDEX
, where PARAMETER_INDEX
starts at 0 for the first parameter, e.g. arg0
, arg1
etc.
Bean Validation providers and integrators are free to provide additional implementations (e.g. based on annotations specifying parameter names, debug symbols etc.). If a user wishes to use another parameter name provider than the default implementation, they may specify the provider to use with help of the bootstrap API (see Bootstrapping) or the XML configuration (see XML configuration: META-INF/validation.xml).
If an exception occurs during invocation of the getParameterNames()
methods, this exception is wrapped into a ValidationException
by the Bean Validation engine.
5.6.3. Declaring return value constraints
Return value constraints are declared by putting constraint annotations directly on a method or constructor.
Some constraints can target both the return value and the array of parameters of an executable. They are known to be both generic and cross-parameter constraints. When using such constraint on an executable to target the return value, one must set validationAppliesTo
in case there is an ambiguity. The set of ambiguities is described in validationAppliesTo. Even without ambiguity, it is recommended to explicitly set validationAppliesTo
to ConstraintTarget.RETURN_VALUE
as it improves readability.
public class OrderService {
private CreditCardProcessor creditCardProcessor;
@ValidOnlineOrderService
public OrderService(OnlineCreditCardProcessor creditCardProcessor) {
this.creditCardProcessor = creditCardProcessor;
}
@ValidBatchOrderService
public OrderService(BatchCreditCardProcessor creditCardProcessor) {
this.creditCardProcessor = creditCardProcessor;
}
@NotNull
@Size(min=1)
public Set<CreditCardProcessor> getCreditCardProcessors() { [...] }
@NotNull
@Future
public Date getNextAvailableDeliveryDate() { [...] }
}
Here the following postconditions are defined which are guaranteed to the caller of the methods and constructors of the OrderService
class:
-
The newly created
OrderService
object returned by the first constructor satisfies the conditions of the custom@ValidOnlineOrderService
constraint. -
The newly created
OrderService
object returned by the second constructor satisfies the conditions of the custom@ValidBatchOrderService
constraint. -
The set of
CreditCardProcessor
objects returned bygetCreditCardProcessors()
will neither be null nor be empty. -
The
Date
object returned bygetNextAvailableDeliveryDate()
will not be null and will be in the future.
Like parameter constraints, these return value constraints are not per-se validated upon method invocation, but instead an integration layer invoking the validation is required.
5.6.4. Marking parameters and return values for cascaded validation
The @Valid
annotation is used to declare that a cascaded validation of the given method/constructor parameters or return values is performed by the Bean Validation provider. When marked, the parameter or return value is considered a bean object to validate. The same rules as for standard object graph validation (see Object graph validation) apply, in particular
-
null arguments and null return values are ignored
-
The validation is recursive; that is, if validated parameter or return value objects have references marked with
@Valid
themselves, these references will also be validated -
Bean Validation providers must guarantee the prevention of infinite loops during cascaded validation
public class OrderService {
@NotNull @Valid
private CreditCardProcessor creditCardProcessor;
@Valid
public OrderService(@NotNull @Valid CreditCardProcessor creditCardProcessor) {
this.creditCardProcessor = creditCardProcessor;
}
@NotNull @Valid
public Order getOrderByPk(@NotNull @Valid OrderPK orderPk) { [...] }
@NotNull
public Set<@Valid Order> getOrdersByCustomer(@NotNull @Valid CustomerPK customerPk) { [...] }
}
Here the following recursive validations will happen when validating the methods of the OrderService
class:
-
Validation of the constraints on the object passed for the
creditCardProcessor
parameter of the constructor -
Validation of the constraints on the newly created
OrderService
instance returned by the constructor, i.e. the@NotNull
constraint on the fieldcreditCardProcessor
and the constraints on the referencedCreditCardProcessor
instance (as the field is annotated with@Valid
). -
Validation of the constraints on the object passed for the
orderPk
parameter and the returnedOrder
object of thegetOrderByPk()
method -
Validation of the constraints on the object passed for the
customerPk
parameter and the constraints on each object contained within the returnedSet<Order>
of thegetOrdersByCustomer()
method
Again, solely marking parameters and return values for cascaded validation does not trigger the actual validation.
5.6.5. Method constraints in inheritance hierarchies
When defining method constraints within inheritance hierarchies (that is, class inheritance by extending base classes and interface inheritance by implementing or extending interfaces) one has to obey the Liskov substitution principle which mandates that:
-
a method’s preconditions (as represented by parameter constraints) must not be strengthened in sub types
-
a method’s postconditions (as represented by return value constraints) must not be weakened in sub types
Tip
|
Very informally speaking, the Liskov substitution principle says that where a given type T is used, it should be possible to replace T with a sub-type S of T ("Behavioral subtyping"). If S overrides/implements a method from T and S would strengthen the method’s preconditions (e.g. by adding parameter constraints) this principle would be violated as client code working correctly against T might fail when working against S. Also if S overrides/implements a method from T and S weakens the method’s postconditions this principle would be violated. However S may strengthen the method’s postconditions (by adding return value constraints), as client code working against T still will work against S. |
Therefore the following rules with respect to the definition of method level constraints in inheritance hierarchies apply:
-
In sub types (be it sub classes/interfaces or interface implementations), no parameter constraints may be declared on overridden or implemented methods, nor may parameters be marked for cascaded validation. This would pose a strengthening of preconditions to be fulfilled by the caller.
-
If a sub type overrides/implements a method originally defined in several parallel types of the hierarchy (e.g. two interfaces not extending each other, or a class and an interface not implemented by said class), no parameter constraints may be declared for that method at all nor parameters be marked for cascaded validation. This again is to avoid an unexpected strengthening of preconditions to be fulfilled by the caller.
-
In sub types (be it sub classes/interfaces or interface implementations), return value constraints may be declared on overridden or implemented methods and the return value may be marked for cascaded validation. Upon validation, all return value constraints of the method in question are validated, wherever they are declared in the hierarchy. This only poses possibly a strengthening but no weakening of the method’s postconditions guaranteed to the caller.
-
One must not mark a method return value for cascaded validation more than once in a line of a class hierarchy. In other words, overriding methods on sub types (be it sub classes/interfaces or interface implementations) cannot mark the return value for cascaded validation if the return value has already been marked on the overridden method of the super type or interface.
Out of the box, a conforming Bean Validation provider must throw a ConstraintDeclarationException
when discovering that any of these rules are violated. In addition providers may implement alternative, potentially more liberal, approaches for handling constrained methods in inheritance hierarchies. Possible means for activating such alternative behavior include provider-specific configuration properties or annotations. Note that client code relying on such alternative behavior is not portable between Bean Validation providers.
The above rules do not apply when validating constructor constraints as constructors do not override one another. Parameter and return value constraints can be applied to any constructor in the type hierarchy, but only the constraints defined directly on the validated constructor are evaluated.
5.6.5.1. Examples
This sections provides some examples of illegal constraint definitions which violate the rules stated above in one way or another.
public interface OrderService {
void placeOrder(String customerCode, Item item, int quantity);
}
public class SimpleOrderService implements OrderService {
@Override
public void placeOrder(
@NotNull @Size(min=3, max=20) String customerCode,
@NotNull Item item,
@Min(1) int quantity) {
[...]
}
}
The constraints in SimpleOrderService
are illegal, as they strengthen the preconditions of the placeOrder()
method as constituted by the interface OrderService
.
public class OrderService {
void placeOrder(String customerCode, Item item, int quantity) { [...] }
}
public class SimpleOrderService extends OrderService {
@Override
public void placeOrder(
@NotNull @Size(min=3, max=20) String customerCode,
@NotNull Item item,
@Min(1) int quantity) {
[...]
}
}
The constraints in SimpleOrderService
are illegal, as they strengthen the preconditions of the placeOrder()
method as constituted by the super class OrderService
.
public interface OrderService {
void placeOrder(String customerCode, Item item, int quantity);
}
public interface OrderPlacementService {
public void placeOrder(
@NotNull @Size(min=3, max=20) String customerCode,
@NotNull Item item,
@Min(1) int quantity);
}
public class SimpleOrderService implements OrderService, OrderPlacementService {
@Override
public void placeOrder(String customerCode, Item item, int quantity) {
[...]
}
}
Here the class SimpleOrderService
implements the interfaces OrderService
and OrderPlacementService
, which themselves are unrelated to each other but both define a method placeOrder()
with an identical signature. This hierarchy is illegal with respect to the parameter constraints as a client of SimpleOrderService
would have to fulfill the constraints defined on the interface OrderPlacementService
even if the client only expects OrderService
.
public class OrderService {
Order placeOrder(String customerCode, Item item, int quantity) {
[...]
}
}
public class SimpleOrderService extends OrderService {
@Override
@NotNull
@Valid
public Order placeOrder(String customerCode, Item item, int quantity) {
[...]
}
}
The return value constraints in DefaultOrderService
are legal, as they strengthen the postconditions of the placeOrder()
method as constituted by the super class OrderService
but don’t weaken them.
5.7. Validation routine
For a given group, the validation routine applied on a given bean instance is expected to execute the following constraint validations in no particular order:
-
for all reachable fields, execute all field level validations (including the ones expressed on superclasses) matching the targeted group unless the given validation constraint has already been processed during this validation routine for a given navigation path (see Object graph validation) as part of a previous group match.
-
for all reachable getters, execute all getter level validations (including the ones expressed on interfaces and superclasses) matching the targeted group unless the given validation constraint has already been processed during this validation routine for a given navigation path (see Object graph validation) as part of a previous group match.
-
execute all class level validations (including the ones expressed on interfaces and superclasses) matching the targeted group unless the given validation constraint has already been processed during this validation routine for a given navigation path (see Object graph validation) as part of a previous group match.
-
for all reachable and cascadable associations, execute all cascading validations (see Object graph validation) including the ones expressed on interfaces and superclasses (see Formal group definitions). Note that group conversion can apply (see Group conversion).
Reachable fields, getters and associations as well as cascadable associations are defined in Traversable property.
Note that this implies that a given validation constraint will not be processed more than once per validation per path. Some implementations might even process a single constraint only once across paths provided that they return the expected set of ConstraintViolation
.
Unless ordered by group sequences, groups can be validated in no particular order. This implies that the validation routine can be run for several groups in the same pass.
The object validation routine is described as such. For each constraint declaration:
-
determine for the constraint declaration, the appropriate
ConstraintValidator
to use (see ConstraintValidator resolution algorithm). -
execute the
isValid
operation (from the constraint validation implementation) on the appropriate data (see Constraint validation implementation) -
if
isValid()
returnstrue
, continue to the next constraint, -
if
isValid()
returnsfalse
, the Bean Validation provider populatesConstraintViolation
object(s) according to the rules defined in Constraint validation implementation and appends these objects to the list of constraint violations.
5.7.1. Object graph validation
The @Valid
annotation on a given association (i.e. object reference or collection, array, Iterable
of objects), dictates the Bean Validator implementation to apply recursively the Bean Validation routine on (each of) the associated object(s). This mechanism is recursive: an associated object can itself contain cascaded references.
Null references are ignored.
To prevent infinite loops, the Bean Validation implementation must ignore the cascading operation if the associated object instance has already been validated in the current navigation path (starting from the root object). See Object graph limits for an example. A navigation path is defined as a set of @Valid
associations starting from the root object instance and reaching the associated instance. A given navigation path cannot contain the same instance multiple times (the complete validated object graph can though). See Object graph limits for an example.
Note
|
This object graph navigation can lead to multiple validations of the same constraint and the same object instance but the set of constraint validation is deterministic and the algorithm prevents infinite loops. |
#assuming the following object graph
Order -(lines)→ Orderline1
Order -(lines)→ Orderline2
Orderline1 -(order)→ Order
Orderline2 -(order)→ Order
Order -(customer)→ User
Order -(shippingAddress)→ Address1
Order -(billingAddress)→ Address2
Address1 -(inhabitant)→ User
Address2 -(inhabitant)→ User
User -(addresses)→ Address1
User -(addresses)→ Address2
#validation branches are as followed
Order -(lines)→ Orderline1
- order is ignored: Order is already present in the branch
Order -(lines)→ Orderline2
- order is ignored: Order is already present in the branch
Order -(customer)→ User -(addresses)→ Address1
- inhabitant is ignored: User is already present in the branch
Order -(customer)→ User -(addresses)→ Address2
- inhabitant is ignored: User is already present in the branch
Order -(shippingAddress)→ Address1 -(inhabitant)→ User
- addresses to Address1 is ignored: Address1 is already present in the branch
Order -(shippingAddress)→ Address1 -(inhabitant)→ User -(addresses)→ Address2
- inhabitant is ignored: User is already present in the branch
Order -(billingAddress)→ Address2 -(inhabitant)→ User
- addresses to Address2 is ignored: Address2 is already present in the branch
Order -(billingAddress)→ Address2 -(inhabitant)→ User -(addresses)→ Address1
- inhabitant is ignored: User is already present in the branch
The ConstraintViolation
objects are built when a failing constraint on an associated object is found. They reflect the path to reach the object from the root validated object (See ConstraintViolation).
@Valid
is an orthogonal concept to the notion of group. If two groups are in sequence, the first group must pass for all associated objects before the second group is evaluated. Note however that the Default
group sequence overriding is local to the class it is defined on and is not propagated to the associated objects. The following example illustrates this:
@GroupSequence({ Minimal.class, Driver.class })
public class Driver {
@Min(value = 18, groups = Minimal.class)
int age;
@AssertTrue
Boolean passedDrivingTest;
@Valid
Car car;
// setter/getters
}
@GroupSequence({ Car.class, Later.class })
public class Car {
@NotNull
String type;
@AssertTrue(groups = Later.class)
Boolean roadWorthy;
// setter/getters
}
@GroupSequence({ Minimal.class, Later.class })
public interface SequencedGroups {
}
Validator validator = Validation.buildDefaultValidatorFactory().getValidator();
Driver driver = new Driver();
driver.setAge(16);
Car porsche = new Car();
driver.setCar(porsche);
Set<ConstraintViolation<Driver>> violations = validator.validate( driver );
assert violations.size() == 2;
violations = validator.validate( driver, SequencedGroups.class );
assert violations.size() == 1;
The default group sequence is redefined for the Driver
as well as Car
. When the default group is requested via validator.validate( driver )
the group Minimal
gets validated in class Driver
. The constraint will fail since the driver’s age in the example is only 16. The constraint on passedDrivingTest
will not be evaluated due to the redefined default sequence of Driver
. However, there is one more constraint violation, namely the @NotNull
on Car.type
. The reason for this is that the group Default
gets propagated to Car
(not Minimal
). Class Driver
defines its own group sequence which means that only @NotNull
on type
gets evaluated.
In the second call to validate
the group SequencedGroups
is requested which defines a sequence of Minimal
followed by Later
. In this case there is only one constraint violation. Again @Min
on age
fails, but in this case the group Minimal
gets propagated to Car
which does not have any constraints defined against this group. Constraints belonging to the group Later
won’t get validated until all constraints belonging to Minimal
pass.
5.7.2. Method and constructor validation
For a given group, the validation routine applied to validate parameters of a method or constructor is expected to execute the following constraint validations in no particular order:
-
execute all parameter validations (in case of overriding method validation, including the ones expressed on overridden methods of the interfaces and superclasses) matching the targeted group unless the given validation constraint has already been processed during this validation routine for a given navigation path (see Object graph validation) as part of a previous group match.
-
execute all cross parameter validations (in case of overriding method validation, including the ones expressed on overridden methods of the interfaces and superclasses) matching the targeted group unless the given validation constraint has already been processed during this validation routine for a given navigation path (see Object graph validation) as part of a previous group match.
-
for all parameters marked for cascaded validation, execute all cascading validations (see Object graph validation), in case of overriding method validation including the ones expressed on overridden methods of the interfaces and superclasses (see Formal group definitions). Note that group conversion can apply (see Group conversion).
For a given group, the validation routine applied to validate the return value of a method or constructor is expected to execute the following constraint validations in no particular order:
-
execute all return value validations (including the ones expressed on interfaces and superclasses) matching the targeted group unless the given validation constraint has already been processed during this validation routine for a given navigation path (see Object graph validation) as part of a previous group match.
-
if the return value is marked for cascaded validation, execute all cascading validations (see Object graph validation) including the ones expressed on interfaces and superclasses (see Formal group definitions). Note that group conversion can apply (see Group conversion).
Note that this implies that a given validation constraint will not be processed more than once per validation per path. Some implementations might even process a single constraint only once across paths provided that they return the expected set of ConstraintViolation
.
Unless ordered by group sequences, groups can be validated in no particular order. This implies that the validation routine can be run for several groups in the same pass.
The object validation routine is as defined in described in Validation routine.
5.7.3. Traversable property
In some cases, the state of some properties should not be accessed. For example, if a property loaded by a Java Persistence provider is a lazy property or a lazy association, accessing its state would trigger a load from the database. An undesired behavior.
Bean Validation offers a way to control which property can and cannot be accessed via the TraversableResolver.isReachable
() contract.
Likewise, it is sometimes undesirable to cascade validation despite the use of @Valid
. Java Persistence 2 for example does not cascade to associated entities during flush. You can control this behavior by implementing TraversableResolver.isCascadable()
.
TraversableResolver
interface/**
* Contract determining if a property can be accessed by the Bean Validation provider.
* This contract is called for each property that is being either validated or cascaded.
* <p>
* A traversable resolver implementation must be thread-safe.
*
* @author Emmanuel Bernard
*/
public interface TraversableResolver {
/**
* Determines if the Bean Validation provider is allowed to reach the property state.
*
* @param traversableObject object hosting {@code traversableProperty}
* or {@code null} if {@code validateValue} is called
* @param traversableProperty the traversable property
* @param rootBeanType type of the root object passed to the Validator
* or hosting the method or constructor validated
* @param pathToTraversableObject path from the root object to
* {@code traversableObject}
* (using the path specification defined by Bean Validator)
* @param elementType either {@code FIELD} or {@code METHOD}
* @return {@code true} if the Bean Validation provider is allowed to
* reach the property state, {@code false} otherwise
*/
boolean isReachable(Object traversableObject,
Node traversableProperty,
Class<?> rootBeanType,
Path pathToTraversableObject,
ElementType elementType);
/**
* Determines if the Bean Validation provider is allowed to cascade validation on
* the bean instance returned by the property value
* marked as {@code @Valid}.
* <p>
* Note that this method is called only if
* {@link #isReachable(Object, javax.validation.Path.Node, Class, Path, java.lang.annotation.ElementType)}
* returns {@code true} for the same set of arguments and if the property
* is marked as {@link Valid}.
*
* @param traversableObject object hosting {@code traversableProperty}
* or {@code null} if {@code validateValue} is called
* @param traversableProperty the traversable property
* @param rootBeanType type of the root object passed to the Validator
* or hosting the method or constructor validated
* @param pathToTraversableObject path from the root object to
* {@code traversableObject}
* (using the path specification defined by Bean Validator)
* @param elementType either {@code FIELD} or {@code METHOD}
* @return {@code true} if the Bean Validation provider is allowed to
* cascade validation, {@code false} otherwise
*/
boolean isCascadable(Object traversableObject,
Node traversableProperty,
Class<?> rootBeanType,
Path pathToTraversableObject,
ElementType elementType);
}
isReachable()
is called for every property about to be accessed either for validation or for cascading. A property is reachable if this method returns true
.
isCascadable()
is called for every property about to be cascaded (i.e. marked as @Valid
). A property is cascadable if it is reachable and if the isCascadable
method returns true
.
Note
|
|
traversableObject
is the object instance being evaluated. null
if the check is triggered as part of a validateValue()
call.
traversableProperty
is the Node
representing the property hosted by the traversableObject
being considered for traversal. The name of a property is defined in Field and property validation.
rootBeanType
is the class of the root being validated, i.e. either the type of the object passed to the validate
method or the type declaring the validated method/constructor in case of method validation.
pathToTraversableObject
is the Path
from the rootBeanType
down to the traversableObject
. If the root object is traversableObject
, pathToTraversableObject
is composed of a single Node whose name is null
. The path is described following the conventions described in ConstraintViolation (getPropertyPath
).
elementType
is the java.lang.annotation.ElementType
the annotation is placed on. It can be either FIELD
or METHOD
. Any other value is not expected.
The Bean Validation provider must not access the state of a property, nor validate its constraints if the property is not traversable. A property is traversable if TraversableResolver
returns true
for this property.
If an exception occurs when the TraversableResolver
is called, the exception is wrapped into a ValidationException
.
The following elements are not passed through the traversable resolver filter:
-
the bean instance validated
-
the method and constructor parameter values being validated
-
the method and constructor return value being validated
But the properties of these elements (if validated) are. In this case the complete path is provided via pathToTraversableObject
.
The traversable resolver used by default by a Bean Validation provider behaves as followed:
-
if Java Persistence is available in the runtime environment, a property is considered reachable if Java Persistence considers the property as loaded. A typical implementation will use
Persistence.getPersistenceUtil().isLoaded(Object, String)
to implement such contract. -
if Java Persistence is not available in the runtime environment, all properties are considered reachable.
-
all properties are considered cascadable.
An example implementation of such a resolver is shown in Java Persistence aware TraversableResolver.
public class JPATraversableResolver implements TraversableResolver {
public boolean isReachable(Object traversableObject,
Path.Node traversableProperty,
Class<?> rootBeanType,
Path pathToTraversableObject,
ElementType elementType) {
return traversableObject == null ||
Persistence.getPersistenceUtil().isLoaded(
traversableObject,
traversableProperty.getName() );
}
public boolean isCascadable(Object traversableObject,
Path.Node traversableProperty,
Class<?> rootBeanType,
Path pathToTraversableObject,
ElementType elementType) {
return true;
}
}
See Bootstrapping to learn how to pass a custom TraversableResolver
.
5.7.3.1. Examples
The following example assumes the object graph defined in Definitions used in the example and assumes the validation operation is applied on an address object.
When the Bean Validation provider is about to check constraints of ISO3Code
, it calls the TraversableResolver.isReachable()
method to ensure that the ISO3Code
property is reachable with the following parameter values:
-
traversableObject
: country. The instance returned byaddress.getCountry()
. -
traversableProperty
: aPropertyNode
whose name is "ISO3Code". Represents the property oftraversableObject
being verified. -
rootBeanType
:Address.class
. The type of the root object being validated. -
pathtoTraversableObject
: aPath
containing a singlePropertyNode
whose name is "country". The path from address to the country instance. -
elementType
:ElementType.FIELD
. The ISO3Code property is annotated on its field.
When the Bean Validation provider is about to cascade validation on country
(Address
object), it calls the TraversableResolver.isReachable()
method to ensure that the country
property is reachable and if this method returns true
, it calls TraversableResolver.isCascadable()
with the following parameter values:
-
traversableObject
: address. The address instance. -
traversableProperty
: aPropertyNode
whose name is "country". Represents the property oftraversableObject
being verified. -
rootBeanType
:Address.class
. The type of the root object being validated. -
pathtoTraversableObject
: aPath
containing a singleBeanNode
whose name isnull
. -
elementType
:ElementType.FIELD
. The country property is annotated on its field.
The following example shows invocations of the TraversableResolver
as to be performed by the Bean Validation provider during method validation. The example is based on the object graph defined in Definitions used in the example and the AddressService
class shown in Examplary class AddressService
. It assumes that a call of persistAddress()
is subject to method parameter validation.
When the Bean Validation provider is about to validate the @NotNull
constraint on the address
parameter, no call to isReachable()
is expected, since parameters are assumed to always be reachable. Similarly, no call to isCascadable()
is expected when performing cascaded validation of the address
parameter, since parameters are assumed to always be cascadable.
When the Bean Validation provider is about to validate constraints on the field addressline1
of the passed Address
object, it calls the isReachable()
method to ensure that the property is reachable with the following parameter values:
-
traversableObject
: address. The instance passed topersistAddress()
. -
traversableProperty
: aPropertyNode
whose name is "addressline1". Represents the property oftraversableObject
being verified. -
rootBeanType
:AddressService.class
. The type of the root object being validated. -
pathtoTraversableObject
: aPath
comprising aMethodNode
(named "persistService") and aParameterNode
(with parameter index 0). The path fromAddressService
to theAddress
instance. -
elementType
:ElementType.FIELD
. Theaddressline1
property is annotated on its field.
When the Bean Validation provider is about to perform a cascaded validation of the country
property of the passed Address
object, it calls the isReachable()
method to ensure that the property is reachable. If this method returns true
, it calls TraversableResolver.isCascadable()
with the following parameter values:
-
traversableObject
: address. The instance passed topersistAddress()
. -
traversableProperty
: aPropertyNode
whose name is "country". Represents the property oftraversableObject
being verified. -
rootBeanType
:AddressService.class
. The type of the root object being validated. -
pathtoTraversableObject
: aPath
comprising aMethodNode
(named "persistService") and aParameterNode
(with parameter index 0). The path fromAddressService
to theAddress
instance. -
elementType
:ElementType.FIELD
. Thecountry
property is annotated on its field.
5.7.4. ConstraintValidator resolution algorithm
A constraint is associated to one or more ConstraintValidator
implementations. Each ConstraintValidator<A, T>
accepts the type T
. The ConstraintValidator
executed depends on the type hosting the constraint. For a given constraint evaluation, a single ConstraintValidator
is considered.
The list of ConstraintValidator
s can contain at most one which targets cross-parameter. If the constraint targets the parameters of an executable either implicitly or by the use of validationAppliesTo
in the constraint - see validationAppliesTo, then the cross-parameter ConstraintValidator
is used. If none is present, a ConstraintDefinitionException
is raised. If more than one cross-parameter ConstraintValidator
is present, a ConstraintDefinitionException
is raised.
If the constraint is a generic constraint, the following rules apply:
-
If the constraint declaration is hosted on a class or an interface, the targeted type is the class or the interface.
-
If the constraint is hosted on a class attribute, the type of the attribute is the targeted type.
-
If the constraint is hosted on a method (getter or non-getter) or constructor, the return type is the targeted type.
-
If the constraint is hosted on a method or constructor parameter, the parameter type is the targeted type.
-
If the constraint is hosted on a type argument of a parameterized type (i.e. a container element constraint, see Container element constraints), the type argument’s type is the targeted type.
-
If the constraint is subject to implicit unwrapping (see Implicit unwrapping of containers) and the applicable value extractor is defined for a generic type (e.g.
javafx.beans.value.ObservableValue
), the targeted type is the type captured for the type parameter handled by the value extractor (e.g.String
if the constraint is placed on aStringProperty
). -
If the constraint is subject to implicit unwrapping and the applicable value extractor is defined for a non-generic type, the targeted type is the type defined by the extractor via
@ExtractedValue#type()
(e.g.Integer
if the constraint is placed on ajava.util.OptionalInt
).
In other words, the resolution algorithm considers the type as defined in the source code and not the runtime type of the value.
The rules written below describe formally the following statement: the ConstraintValidator
chosen to validate the generic constraint on a declared type T
is the one where the ConstraintValidator
targets the annotated element, where the type supported by the ConstraintValidator
is a supertype of T
and where there is no other ConstraintValidator
whose supported type is a supertype of T
and not a supertype of the chosen ConstraintValidator
supported type.
When validating a generic constraint A
placed on a target declaring the type T
, the following resolution rules apply:
-
Only
ConstraintValidator
implementations targeting annotated elements are considered. -
Primitive types are considered equivalent to their respective primitive wrapper class.
-
A
ConstraintValidator<A, U>
is said to be compliant withT
ifT
is a subtype ofU
(according to the Java Language Specification, Java SE 8 Edition, chapter 4.10, "Subtyping"). Note thatT
is a subtype ofU
ifT
=U
. -
If no
ConstraintValidator
compliant withT
is found among theConstraintValidator
s listed by the constraintA
, anUnexpectedTypeException
is raised. -
A
ConstraintValidator<A, U>
compliant withT
is considered strictly more specific than aConstraintValidator<A, V>
compliant withT
ifU
is a strict subtype ofV
.U
is a strict subtype ofV
ifU
is a subtype ofV
andU
!=V
(according to the Java Language Specification). -
A
ConstraintValidator<A, U>
compliant withT
is considered maximally specific if no otherConstraintValidator<A, V>
compliant withT
is strictly more specific thanConstraintValidator<A, U>
. -
If more than one maximally specific
ConstraintValidator
is found, anUnexpectedTypeException
is raised.
Note
|
While the Java compiler itself cannot determine if a constraint declaration will lead to a |
Let’s see a couple of declarations and their respective ConstraintValidator
resolution. Assuming the definitions shown in ConstraintValidator and type resolution:
[...]
@Constraint(validatedBy={
SizeValidatorForCollection.class,
SizeValidatorForSet.class,
SizeValidatorForSerializable.class })
public @interface Size { [...] }
public class SizeValidatorForCollection implements ConstraintValidator<Size, Collection> {
[...]
}
public class SizeValidatorForSet implements ConstraintValidator<Size, Set> {
[...]
}
public class SizeValidatorForSerializable implements ConstraintValidator<Size, Serializable> {
[...]
}
public interface SerializableCollection extends Serializable, Collection {
}
The resolutions shown in Resolution of ConstraintValidator for various constraints declarations occur.
Declaration | Resolution |
---|---|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
5.7.5. ValueExtractor resolution
When detecting a container element constraint or a container element marked with @Valid
, a value extractor must be determined so that the elements can be obtained from that container.
A value extractor handles one container type and - in the case of a generic container type - one type parameter of that container type.
The applicable extractor is identified based on the container type and - in the case of a generic container type - the type argument hosting the container element constraint or @Valid
.
Exactly one value extractor must be identified when processing a container element constraint or container element marked with @Valid
.
5.7.5.1. Registering ValueExtractor implementations
Value extractors can be registered with the validation engine in the following ways (in increasing order of priority):
-
Provided by the validation engine itself (see Built-in value extractors)
-
Via the Java service loader mechanism; for this the file META-INF/services/javax.validation.valueextraction.ValueExtractor must be provided, with the fully-qualified name(s) of one or more extractor implementations as its contents. It is undefined which value extractor will be selected if multiple extractors for the same type and type parameter are registered via the service loader mechanism.
-
By specifying the fully-qualified class name of one or several extractors in
META-INF/validation.xml
(see XML configuration: META-INF/validation.xml). Not more than one extractor for the same type and type parameter may be given. -
By invoking the method
Configuration#addValueExtractor(ValueExtractor<?>)
(to apply it at the validator factory level). Not more than one extractor for the same type and type parameter may be passed. -
By invoking the method
ValidatorContext#addValueExtractor(ValueExtractor<?>)
(to apply it for a singleValidator
instance). Not more than one extractor for the same type and type parameter may be passed.
A value extractor for a given type and type parameter specified at a higher priority overrides any other extractors for the same type and type parameter given at lower priorities.
If e.g. a value extractor defined as class MyListValueExtractor implements ValueExtractor<List<@ExtractedValue ?>> { … }
is given via ValidatorContext#addValueExtractor(ValueExtractor<?>)
,
it will take precedence over any other value extractor implementing List<@ExtractedValue ?>
given via Configuration#addValueExtractor(ValueExtractor<?>)
,
META-INF/validation.xml or the service loader mechanism as well as the built-in extractor for List
values.
5.7.5.2. ValueExtractor resolution algorithm for container element constraints
For a container with the declared type C
whose element type is hosting a constraint, the following resolution rules apply for identifying the value extractor:
-
A
ValueExtractor<T>
is said to be type-compliant withC
, ifC
is a subtype ofT
(according to the Java Language Specification, Java SE 8 Edition, chapter 4.10, "Subtyping"). Note thatC
is a subtype ofT
ifC
=T
. -
A
ValueExtractor
implementation is said to be container-element-compliant withC
, ifC
is a generic container type and the value extractor implementation handles a type parameter that maps to the constrained type argument. -
If no
ValueExtractor
type-compliant and container-element-compliant withC
is found among the available value extractors, aConstraintDeclarationException
is raised. -
A
ValueExtractor<U>
type-compliant withC
is considered strictly more specific than aValueExtractor<V>
compliant withC
ifU
is a strict subtype ofV
.U
is a strict subtype ofV
ifU
is a subtype ofV
andU
!=V
. -
A
ValueExtractor<U>
type-compliant withC
is considered maximally specific if no otherValueExtractor<V>
type-compliant withC
is strictly more specific thanValueExtractor<U>
. -
If more than one maximally specific and container-element-compliant
ValueExtractor
is found, aConstraintDeclarationException
is raised.
Note
|
Implementation note
Extractor retrieval for container element constraints is based on the declared type of constrained elements, hence it is recommended that implementations perform the resolution once and then cache the value extractor for a given constraint. |
5.7.5.3. ValueExtractor resolution algorithm for cascaded validation
For a container with the declared type C
and the runtime type C'
whose element type is marked for cascaded validation, the following resolution rules apply for identifying the value extractor:
-
A
ValueExtractor<T>
is said to be type-compliant withC'
, ifC'
is a subtype ofT
. Note thatC'
is a subtype ofT
ifC'
=T
. -
A
ValueExtractor
implementation is said to be container-element-compliant withC
, if it handles a type parameter that maps to the type argument marked with@Valid
. -
If no
ValueExtractor
type-compliant withC'
and container-element-compliant withC
is found among the available value extractors, aConstraintDeclarationException
is raised. -
A
ValueExtractor<U>
type-compliant withC'
is considered strictly more specific than aValueExtractor<V>
compliant withC'
ifU
is a strict subtype ofV
.U
is a strict subtype ofV
ifU
is a subtype ofV
andU
!=V
. -
A
ValueExtractor<U>
type-compliant withC'
is considered maximally specific if no otherValueExtractor<V>
type-compliant withC'
is strictly more specific thanValueExtractor<U>
. -
If more than one maximally specific and container-element-compliant
ValueExtractor
is found, aConstraintDeclarationException
is raised.
Note
|
Implementation note
Extractor retrieval for cascaded validation is based on the runtime type of the container hosting |
5.7.5.4. ValueExtractor resolution algorithm for applying container-level constraints to container elements
When detecting a constraint given as a declaration annotation and not as a type annotation (i.e. it is given on field, parameter etc. and not given on an a type argument of a parameterized type), the applicable value extractor, if any, is determined as follows:
-
If the constraint carries the
Unwrapping.Skip
payload, no value extractor is applied. -
If the constraint carries the
Unwrapping.Unwrap
payload and there is exactly one maximally-specific type-compliant value extractor, this extractor is applied; if no type-compliant extractor or multiple maximally-specific type-compliant extractors exist, aConstraintDeclarationException
is raised. -
If the constraint carries neither the
Unwrapping.Unwrap
nor theUnwrapping.Skip
payload:-
If there is exactly one maximally-specific type-compliant value extractor and this extractor is marked with
@UnwrapByDefault
, this extractor is applied; -
Otherwise, no value extractor is applied.
-
5.7.5.5. Examples
Let’s consider a couple of value extractor definitions and their respective ValueExtractor
resolution against container element constraint declarations:
ValueExtractor
resolutionpublic interface ConcurrentList<T> {
[...]
}
public class MyList<T> implements List<T>, ConcurrentList<T> {
[...]
}
public interface Table<R, C, V> {
[...]
}
interface ConfusingMap<K, V> extends Map<V, K> {
[...]
}
interface SingleTypeMap<T> extends Map<T, T> {
[...]
}
interface StringMap extends Map<String, String> {
[...]
}
interface Property<T> {
[...]
}
class StringProperty implements Property<String> {
[...]
}
public class IterableValueExtractor implements ValueExtractor<Iterable<@ExtractedValue ?>> {
[...]
}
public class ListValueExtractor implements ValueExtractor<List<@ExtractedValue ?>> {
[...]
}
public class ConcurrentListValueExtractor implements ValueExtractor<
ConcurrentList<@ExtractedValue ?>> {
[...]
}
public class MapKeyExtractor implements ValueExtractor<Map<@ExtractedValue ?, ?>> {
[...]
}
public class MapValueExtractor implements ValueExtractor<Map<?, @ExtractedValue ?>> {
[...]
}
public class TableValueExtractor implements ValueExtractor<Table<?, ?, @ExtractedValue ?>> {
[...]
}
@UnwrapByDefault
public class PropertyValueExtractor implements ValueExtractor<Property<@ExtractedValue ?>> {
[...]
}
@UnwrapByDefault
public class OptionalIntValueExtractor implements ValueExtractor<
@ExtractedValue(type = Integer.class) OptionalInt> {
[...]
}
The following value extractor resolutions occur:
Declaration | Resolution |
---|---|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
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5.8. Examples
The first example demonstrates how beans, fields and getters are annotated to express some constraints.
@ZipCodeCityCoherenceChecker
public class Address {
@NotNull @Size(max=30)
private String addressline1;
@Size(max=30)
private String addressline2;
private String zipCode;
private String city;
public String getAddressline1() {
return addressline1;
}
public void setAddressline1(String addressline1) {
this.addressline1 = addressline1;
}
public String getAddressline2() {
return addressline2;
}
public void setAddressline2(String addressline2) {
this.addressline2 = addressline2;
}
public String getZipCode() {
return zipCode;
}
public void setZipCode(String zipCode) {
this.zipCode = zipCode;
}
@Size(max=30) @NotNull
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
}
During the validation routine execution on an Address
object,
-
addressline1
field value is passed to the@NotNull
as well as@Size
constraint validation implementations. -
addressline2
field value is passed to the@Size
constraint validation implementation. -
getCity
value is passed to the@Size
and@NotNull
constraint validation implementations. -
@ZipCodeCoherenceChecker
is a constraint whose validation implementation’sisValid
method receives theAddress
object.
The second example demonstrates object graph validation.
public class Country {
@NotNull
private String name;
@Size(max=2)
private String ISO2Code;
@Size(max=3)
private String ISO3Code;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getISO2Code() {
return ISO2Code;
}
public void setISO2Code(String ISO2Code) {
this.ISO2Code = ISO2Code;
}
public String getISO3Code() {
return ISO3Code;
}
public void setISO3Code(String ISO3Code) {
this.ISO3Code = ISO3Code;
}
}
public class Address {
@NotNull @Size(max=30)
private String addressline1;
@Size(max=30)
private String addressline2;
@Size(max=11)
private String zipCode;
@NotNull @Valid
private Country country;
private String city;
public String getAddressline1() {
return addressline1;
}
public void setAddressline1(String addressline1) {
this.addressline1 = addressline1;
}
public String getAddressline2() {
return addressline2;
}
public void setAddressline2(String addressline2) {
this.addressline2 = addressline2;
}
public String getZipCode() {
return zipCode;
}
public void setZipCode(String zipCode) {
this.zipCode = zipCode;
}
@Size(max=30) @NotNull
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public Country getCountry() {
return country;
}
public void setCountry(Country country) {
this.country = country;
}
}
During the validation routine execution on an Address
object, constraints on addressLine1
, addressLine2
, zipCode
, getCity
and country
are processed as well as the validation of the Country
object itself, more specifically country.name
is checked for @NotNull
, ISO2Code
and ISO3Code
are checked for @Size
.
Assuming that @NonEmpty
is defined as such:
@Documented
@NotNull
@Size(min = 1)
@ReportAsSingleViolation
@Constraint(validatedBy = NonEmpty.NonEmptyValidator.class)
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
public @interface NonEmpty {
String message() default "{com.acme.constraint.NonEmpty.message}";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
NonEmpty[] value();
}
class NonEmptyValidator implements ConstraintValidator<NonEmpty, String> {
@Override
public boolean isValid(String value, ConstraintValidatorContext context) {
return true;
}
}
}
The third example demonstrates superclass, inheritance and composite constraints.
public interface Person {
@NonEmpty
String getFirstName();
String getMiddleName();
@NonEmpty
String getLastName();
}
public class Customer implements Person {
private String firstName;
private String middleName;
private String lastName;
@NotNull
private String customerId;
@Password(robustness=5)
private String password;
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getMiddleName() {
return middleName;
}
public void setMiddleName(String middleName) {
this.middleName = middleName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String getCustomerId() {
return customerId;
}
public void setCustomerId(String customerId) {
this.customerId = customerId;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
public class PreferredGuest extends Customer {
@CreditCard
private String guestCreditCardNumber;
public String getGuestCreditCardNumber() {
return guestCreditCardNumber;
}
public void setGuestCreditCardNumber(String guestCreditCardNumber) {
this.guestCreditCardNumber = guestCreditCardNumber;
}
}
public class CommonGuest extends customer {}
When validating a PreferredGuest
the following constraints are processed:
-
@NonEmpty
,@NotNull
and@Size(min=1)
onfirstName
-
@NonEmpty
,@NotNull
and@Size(min=1)
onlastName
-
@NotNull
oncustomerId
,@Password
onpassword
-
@CreditCard
onguestCreditCardNumber
When validating CommonGuest
, the following constraints are processed:
-
@NonEmpty
,@NotNull
and@Size(min=1)
onfirstName
-
@NonEmpty
,@NotNull
and@Size(min=1)
onlastName
-
@NotNull
oncustomerId
,@Password
onpassword
The fourth example demonstrates the influence of group sequence.
@GroupSequence({First.class, Second.class, Last.class})
public interface Complete {}
public class Book {
@NonEmpty(groups=First.class)
private String title;
@Size(max=30, groups=Second.class)
private String subtitle;
@Valid
@NotNull(groups=First.class)
private Author author;
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getSubtitle() {
return subtitle;
}
public void setSubtitle(String subtitle) {
this.subtitle = subtitle;
}
public Author getAuthor() {
return author;
}
public void setAuthor(Author author) {
this.author = author;
}
}
public class Author {
@NonEmpty(groups=Last.class)
private String firstName;
@NonEmpty(groups=First.class)
private String lastName;
@Size(max=30, groups=Last.class)
private String company;
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String getCompany() {
return company;
}
public void setCompany(String company) {
this.company = company;
}
}
Assuming the validation of the Complete
group on the following book instance:
Author author = new Author();
author.setLastName( "Baudelaire" );
author.setFirstName( "" );
Book book = new Book();
book.setAuthor( author );
the validation routine will return the following failure:
-
@NotNull
failure (from@NonEmpty
) on thetitle
field
As both title
and author.lastname
are checked as part of the First
group. If the instance is updated:
book.setTitle( "Les fleurs du mal" );
author.setCompany( "Some random publisher with a very very very long name" );
the validation routine will return the following failures:
-
author.firstName
fails to pass the@Size(min=1)
(from@NonEmpty
) constraint -
author.company
fails to pass the@Size
constraint
As the First
and Second
groups pass without failure, the Last
group is going through validation.
6. Validation APIs
The default package for the Bean Validation APIs is javax.validation
.
6.1. Validator API
The main Bean Validation API is the javax.validation.Validator
interface.
A Validator
instance is able to validate instances of beans and their associated objects if any. It is recommended to leave the caching of Validator
instances to the ValidatorFactory
. Validator
implementations must be thread-safe.
Validator
interface/**
* Validates bean instances. Implementations of this interface must be thread-safe.
*
* @author Emmanuel Bernard
* @author Hardy Ferentschik
* @author Gunnar Morling
*/
public interface Validator {
/**
* Validates all constraints on {@code object}.
*
* @param object object to validate
* @param groups the group or list of groups targeted for validation (defaults to
* {@link Default})
* @param <T> the type of the object to validate
* @return constraint violations or an empty set if none
* @throws IllegalArgumentException if object is {@code null}
* or if {@code null} is passed to the varargs groups
* @throws ValidationException if a non recoverable error happens
* during the validation process
*/
<T> Set<ConstraintViolation<T>> validate(T object, Class<?>... groups);
/**
* Validates all constraints placed on the property of {@code object}
* named {@code propertyName}.
*
* @param object object to validate
* @param propertyName property to validate (i.e. field and getter constraints)
* @param groups the group or list of groups targeted for validation (defaults to
* {@link Default})
* @param <T> the type of the object to validate
* @return constraint violations or an empty set if none
* @throws IllegalArgumentException if {@code object} is {@code null},
* if {@code propertyName} is {@code null}, empty or not a valid object property
* or if {@code null} is passed to the varargs groups
* @throws ValidationException if a non recoverable error happens
* during the validation process
*/
<T> Set<ConstraintViolation<T>> validateProperty(T object,
String propertyName,
Class<?>... groups);
/**
* Validates all constraints placed on the property named {@code propertyName}
* of the class {@code beanType} would the property value be {@code value}.
* <p>
* {@link ConstraintViolation} objects return {@code null} for
* {@link ConstraintViolation#getRootBean()} and
* {@link ConstraintViolation#getLeafBean()}.
*
* @param beanType the bean type
* @param propertyName property to validate
* @param value property value to validate
* @param groups the group or list of groups targeted for validation (defaults to
* {@link Default}).
* @param <T> the type of the object to validate
* @return constraint violations or an empty set if none
* @throws IllegalArgumentException if {@code beanType} is {@code null},
* if {@code propertyName} is {@code null}, empty or not a valid object property
* or if {@code null} is passed to the varargs groups
* @throws ValidationException if a non recoverable error happens
* during the validation process
*/
<T> Set<ConstraintViolation<T>> validateValue(Class<T> beanType,
String propertyName,
Object value,
Class<?>... groups);
/**
* Returns the descriptor object describing bean constraints.
* <p>
* The returned object (and associated objects including
* {@link ConstraintDescriptor}s) are immutable.
*
* @param clazz class or interface type evaluated
* @return the bean descriptor for the specified class
* @throws IllegalArgumentException if clazz is {@code null}
* @throws ValidationException if a non recoverable error happens
* during the metadata discovery or if some
* constraints are invalid.
*/
BeanDescriptor getConstraintsForClass(Class<?> clazz);
/**
* Returns an instance of the specified type allowing access to
* provider-specific APIs.
* <p>
* If the Bean Validation provider implementation does not support
* the specified class, {@link ValidationException} is thrown.
*
* @param type the class of the object to be returned
* @param <T> the type of the object to be returned
* @return an instance of the specified class
* @throws ValidationException if the provider does not support the call
*/
<T> T unwrap(Class<T> type);
/**
* Returns the contract for validating parameters and return values of methods
* and constructors.
*
* @return contract for method and constructor validation
*
* @since 1.1
*/
ExecutableValidator forExecutables();
}
The methods validate()
, validateProperty()
and validateValue()
are used for the validation of Java beans respectively single bean properties. See the next section for more details.
forExecutables()
provides access to the contract for validating method and constructor parameters and return values. The individual methods for method and constructor validation are described in Methods for validating method and constructor constraints.
getConstraintsForClass()
returns constraint-related metadata for given types and is described in detail in Constraint metadata request APIs.
unwrap()
is provided as a way to access objects of a given type specific to a Bean Validation provider typically as a complement to the Validator
contract. Using this method makes your code non portable.
//if using the ACME provider
ACMEValidator acmeValidator = factory.unwrap(ACMEValidator.class);
acmeValidator.setSpecificConfiguration( [...] );
6.1.1. Validation methods
<T> Set<ConstraintViolation<T>> validate(T object, Class<?>... groups)
is used to validate a given object. This method implements the logic described in Validation routine. An IllegalArgumentException
is thrown when null is passed for the object
parameter or the varargs groups
parameter. A Set
containing all ConstraintViolation
objects representing the failing constraints is returned, an empty Set
is returned otherwise.
<T> Set<ConstraintViolation<T>> validateProperty(T object, String propertyName, Class<?>... groups)
validates a given field or property of an object. An IllegalArgumentException
is thrown when validateProperty()
is called and object
is null or propertyName
is null, empty or invalid or null is passed to the varargs groups
parameter. The property name is the JavaBeans property name (as defined by the JavaBeans Introspector
class). This method implements the logic described in Validation routine but only to the given property. @Valid
is not honored by this method. This method is useful for partial object validation.
<T> Set<ConstraintViolation<T>> validateValue(Class<T> beanType, String propertyName, Object value, Class<?>... groups)
validates the property referenced by propertyName
present on beanType
or any of its superclasses, if the property value were value
. An IllegalArgumentException
is thrown when validateValue()
is called and beanType
is null or propertyName
is null, empty or invalid or null is passed to the varargs groups
parameter. This method implements the logic described in Validation routine and apply it only to the given property and for the given value. @Valid
is not honored by this method. This method is useful for ahead of time validation (i.e. before the JavaBean is populated or updated).
Note
|
If multiple constrained fields or getters share the same name and hide one another in the class hierarchy according to the Java visibility rules, the list of constraints evaluated is unspecified. This will be clarified in a later version of this specification. Note that method overriding is not impacted. If getters and fields share the same name and are present at different levels of the hierarchy, the list of constraints evaluated is unspecified. This will be clarified in a later version of this specification. However, constraints hosted on the most specific (hierarchy wise) element type are always evaluated. |
Note
|
|
If some unrecoverable failure happens during validation, a ValidationException
is raised. This exception can be specialized in some situations (invalid group definition, invalid constraint definition, invalid constraint declaration). See Exception model or the relative sections for more information.
6.1.1.1. Examples
All the examples will be based on the following class definition, constraint declarations and address instance.
public class Address {
@NotNull @Size(max=30)
private String addressline1;
@Size(max=30)
private String addressline2;
private String zipCode;
private String city;
public String getAddressline1() {
return addressline1;
}
public void setAddressline1(String addressline1) {
this.addressline1 = addressline1;
}
public String getAddressline2() {
return addressline2;
}
public void setAddressline2(String addressline2) {
this.addressline2 = addressline2;
}
public String getZipCode() {
return zipCode;
}
public void setZipCode(String zipCode) {
this.zipCode = zipCode;
}
@Size(max=30) @NotNull
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
}
Address address = new Address();
address.setAddressline1( null );
address.setAddressline2( null );
address.setCity("Llanfairpwllgwyngyllgogerychwyrndrobwyll-llantysiliogogogoch");
//town in North Wales
The following code will return two ConstraintViolation
objects. One for addressline1
violating @NotNull
and one for city
violating @Size
.
validator.validate(address).size() == 2
The following code will return one ConstraintViolation
since city
violates @Size
and only city
is validated.
validator.validateProperty(address, "city").size() == 1
The following code will return no ConstraintViolation
objects because the value "Paris" for city
would not raise any constraint failures.
validator.validateValue(Address.class, "city", "Paris").size() == 0
6.1.2. Methods for validating method and constructor constraints
The methods for the validation of parameters and return values of methods and constructors can be found on the interface javax.validation.executable.ExecutableValidator
.
ExecutableValidator
interfacepackage javax.validation.executable;
/**
* Validates parameters and return values of methods and constructors.
* Implementations of this interface must be thread-safe.
*
* @author Gunnar Morling
* @since 1.1
*/
public interface ExecutableValidator {
/**
* Validates all constraints placed on the parameters of the given method.
*
* @param <T> the type hosting the method to validate
* @param object the object on which the method to validate is invoked
* @param method the method for which the parameter constraints is validated
* @param parameterValues the values provided by the caller for the given method's
* parameters
* @param groups the group or list of groups targeted for validation (defaults to
* {@link Default})
* @return a set with the constraint violations caused by this validation;
* will be empty if no error occurs, but never {@code null}
* @throws IllegalArgumentException if {@code null} is passed for any of the parameters
* or if parameters don't match with each other
* @throws ValidationException if a non recoverable error happens during the
* validation process
*/
<T> Set<ConstraintViolation<T>> validateParameters(T object,
Method method,
Object[] parameterValues,
Class<?>... groups);
/**
* Validates all return value constraints of the given method.
*
* @param <T> the type hosting the method to validate
* @param object the object on which the method to validate is invoked
* @param method the method for which the return value constraints is validated
* @param returnValue the value returned by the given method
* @param groups the group or list of groups targeted for validation (defaults to
* {@link Default})
* @return a set with the constraint violations caused by this validation;
* will be empty if no error occurs, but never {@code null}
* @throws IllegalArgumentException if {@code null} is passed for any of the object,
* method or groups parameters or if parameters don't match with each other
* @throws ValidationException if a non recoverable error happens during the
* validation process
*/
<T> Set<ConstraintViolation<T>> validateReturnValue(T object,
Method method,
Object returnValue,
Class<?>... groups);
/**
* Validates all constraints placed on the parameters of the given constructor.
*
* @param <T> the type hosting the constructor to validate
* @param constructor the constructor for which the parameter constraints is validated
* @param parameterValues the values provided by the caller for the given constructor's
* parameters
* @param groups the group or list of groups targeted for validation (defaults to
* {@link Default})
* @return a set with the constraint violations caused by this validation;
* Will be empty if no error occurs, but never {@code null}
* @throws IllegalArgumentException if {@code null} is passed for any of the parameters
* or if parameters don't match with each other
* @throws ValidationException if a non recoverable error happens during the
* validation process
*/
<T> Set<ConstraintViolation<T>> validateConstructorParameters(Constructor<? extends T> constructor,
Object[] parameterValues,
Class<?>... groups);
/**
* Validates all return value constraints of the given constructor.
*
* @param <T> the type hosting the constructor to validate
* @param constructor the constructor for which the return value constraints is validated
* @param createdObject the object instantiated by the given method
* @param groups the group or list of groups targeted for validation (defaults to
* {@link Default})
* @return a set with the constraint violations caused by this validation;
* will be empty, if no error occurs, but never {@code null}
* @throws IllegalArgumentException if {@code null} is passed for any of the parameters
* or if parameters don't match with each other
* @throws ValidationException if a non recoverable error happens during the
* validation process
*/
<T> Set<ConstraintViolation<T>> validateConstructorReturnValue(Constructor<? extends T> constructor,
T createdObject,
Class<?>... groups);
}
<T> Set<ConstraintViolation<T>> validateParameters(T object, Method method, Object[] parameterValues, Class<?>... groups)
validates the arguments (as given in parameterValues
) for the parameters of a given method (identified by method
). Cross-parameter constraints are also validated. A set containing all ConstraintViolation
objects representing the failing constraints is returned, an empty set is returned if no constraint violations occurred. An IllegalArgumentException
will be thrown if null is passed for any of the parameters or if the parameters don’t match with each other (i.e. object
and method
don’t match, parameterValues
and method
don’t match).
<T> Set<ConstraintViolation<T>> validateReturnValue(T object, Method method, Object returnValue, Class<?>... groups)
validates the return value (specified by returnValue
) of a given method (identified by method
). A set containing all ConstraintViolation
objects representing the failing constraints is returned, an empty set is returned if no constraint violations occurred. An IllegalArgumentException
will be thrown if null is passed for any of the parameters object
, method
and groups
or if the parameters don’t match with each other (i.e. object
and method
don’t match, returnValue
and method
don’t match).
<T> Set<ConstraintViolation<T>> validateConstructorParameters(Constructor<T> constructor, Object[] parameterValues, Class<?>... groups)
validates the arguments (as given in parameterValues
) for the parameters of a given constructor (identified by constructor
). Cross-parameter constraints are also validated. A set containing all ConstraintViolation
objects representing the failing constraints is returned, an empty set is returned if no constraint violations occurred. An IllegalArgumentException
will be thrown if null is passed for any of the parameters or if the parameters don’t match with each other (i.e. parameterValues
and constructor
don’t match).
<T> Set<ConstraintViolation<T>> validateConstructorReturnValue(Constructor<T> constructor, T createdObject, Class<?>... groups)
validates the object (specified by createdObject
) of a given constructor (identified by constructor
). A set containing all ConstraintViolation
objects representing the failing constraints is returned, an empty set is returned if no constraint violations occurred. An IllegalArgumentException
will be thrown if null is passed for any of the parameters or if the parameters don’t match with each other (i.e. createdObject
and constructor
don’t match).
None of those methods honor the XML configuration around executable validation nor the presence of @ValidateOnExecution
. In other words, elements will be validated regardless of these settings when explicitly calling the validation methods.
6.1.2.1. Examples
All the examples will be based on the following class definitions, constraint declarations and instances.
public class OrderService {
@NotNull
private CreditCardProcessor creditCardProcessor;
@Valid
public OrderService(@NotNull CreditCardProcessor creditCardProcessor) {
[...]
}
@NotNull
public Order placeOrder(
@NotNull @Size(min=3, max=20) String customerCode,
@NotNull @Valid Item item,
@Min(1) int quantity) {
[...]
}
}
public class Item {
@NotNull;
private String name;
public String getName() { return name; }
public void setName(String name) { this.name = name; }
}
Item item1 = new Item();
item1.setName("Kiwi");
Item item2 = new Item();
item2.setName(null);
Constructor<OrderService> constructor = [...]; //get constructor object
Method placeOrder = [...]; //get method object
OrderService orderService = new OrderService(new DefaultCreditCardProcessor());
ExecutableValidator executableValidator = Validation
.buildDefaultValidatorFactory().getValidator().forExecutables();
The following method parameter validation will return one ConstraintViolation
object as the customer code is null:
//orderService.placeOrder(null, item1, 1);
executableValidator.validateParameters(
orderService, placeOrder, new Object[] { null, item1, 1 }).size() == 1;
The following method parameter validation will return one ConstraintViolation
object as the item
parameter is marked for cascaded validation and the given Item
instance is not valid (its name is null):
//orderService.placeOrder("CUST-123", item2, 1);
executableValidator.validateParameters(
orderService, placeOrder, new Object[] { "CUST-123", item2, 1 }).size() == 1;
The following constructor parameter validation will return one ConstraintViolation
object as null is passed for the creditCardProcessor
parameter:
//new OrderService(null);
executableValidator.validateConstructorParameters(constructor, new Object[] { null })
.size() == 1;
Assuming the placeOrder()
method returned null
, the following return value validation will return one ConstraintViolation
:
executableValidator.validateReturnValue(orderService, placeOrder, null).size() == 1;
Assuming the constructor of OrderService
failed to store the given credit card processor into the creditCardProcessor
field, the following validation of the constructor return value would fail as the constructor is marked with @Valid
and the @NotNull
constraint of the OrderService
class would be violated:
executableValidator.validateConstructorReturnValue(constructor, orderService).size() == 1;
Let’s now look at how a validation interceptor would use these methods.
@Interceptor
public class SampleMethodInterceptor {
@Inject
private Validator validator;
@AroundInvoke
public Object validateMethodInvocation(InvocationContext ctx) throws Exception {
//validate parameters
Set<ConstraintViolation<Object>> violations;
violations = validator.forExecutables().validateParameters(
ctx.getTarget(),
ctx.getMethod(),
ctx.getParameters()
);
//if a violation occurs for parameters, raise an exception
if ( !violations.isEmpty() ) {
throw new ConstraintViolationException(
buildMessage( ctx.getMethod(), ctx.getParameters(), violations ),
violations
);
}
//execute the method proper
Object result = ctx.proceed();
//validate the return type
violations = validator.forExecutables().validateReturnValue(
ctx.getTarget(),
ctx.getMethod(),
result
);
//if a violation occurs for the return type, raise an exception
if ( !violations.isEmpty() ) {
throw new ConstraintViolationException(
buildMessage( ctx.getMethod(), ctx.getParameters(), violations ),
violations
);
}
//return the result
return result;
}
}
6.1.3. groups
Groups allow you to restrict the set of constraints applied during validation. Groups targeted are passed as parameters to the validate()
, validateProperty()
and validateValue()
methods as well as the methods to validate method/constructor constraints (see Methods for validating method and constructor constraints). All constraints belonging to the targeted group(s) are applied during the Validation routine. If no group is passed, the Default
group is assumed. groups describes how to define groups on constraints.
When more than one group is evaluated and passed to the various validate methods, order is not constrained. It is equivalent to the validation of a group G
inheriting all groups (i.e. implementing all interfaces) passed to the validation method.
6.1.3.1. Examples
/** Validates a minimal set of constraints */
public interface Minimal {}
public class Address {
@NonEmpty(groups = Minimal.class)
@Size(max=50)
private String street1;
@NonEmpty
private String city;
@NonEmpty(groups = {Minimal.class, Default.class})
private String zipCode;
[...]
}
In the previous example, @NonEmpty
(and its composing constraints, assuming the definition given in chapter Constraint declaration and validation process) on street1
applies to the group Minimal
, @Size
on street1
applies to the group Default
and @NonEmpty
(and its composing constraints) on zipCode
applies to the groups Default
and Minimal
.
validator.validate(address);
validates the group Default
(implicitly) and applies @Size
on street1
, @NonEmpty
(and its composing constraints) on city
, @NonEmpty
(and its composing constraints) on zipCode
. Particularly, @NonEmpty
(and its composing constraints) on street1
are not applied.
validator.validate(address, Minimal.class);
applies @NonEmpty
(and its composing constraints) on street1
and @NonEmpty
(and its composing constraints) on zipCode
because they belong to the Minimal
group.
validator.validate(address, Minimal.class, Default.class);
validates both Default
and Minimal
groups. The routine applies @NonEmpty
(and its composing constraints) and @Size
on street1
, @NonEmpty
(and its composing constraints) on city
, @NonEmpty
(and its composing constraints) on zipCode
. Note that if zipCode
is empty, only one ConstraintViolation
object will represent the failure and the not empty validation will only be executed once.
Let’s look at a more complex example involving group sequence.
public class Address {
@NonEmpty(groups = Minimal.class)
@Size(max=50, groups=FirstStep.class)
private String street1;
@NonEmpty(groups=SecondStep.class)
private String city;
@NonEmpty(groups = {Minimal.class, SecondStep.class})
private String zipCode;
[...]
public interface FirstStep {}
public interface SecondStep {}
@GroupSequence({Firststep.class, SecondStep.class})
public interface Total {}
}
When running:
validator.validate(address, Minimal.class, Total.class);
the validation process will process @NonEmpty
(and its composing constraints) and @Size
from street1
and @NonEmpty
(and its composing constraints) from zipCode
. If @Size
from street1
does not generate a failure, then @NonEmpty
(and its composing constraints) from city
will be processed as part of SecondStep
. Note that @NonEmpty
(and its composing constraints) from zipCode
are not reprocessed as they have already been processed before.
When running:
validator.validate(address, Total.class, SecondStep.class);
@NonEmpty
(and its composing constraints) from city
and @NonEmpty
(and its composing constraints) from zipCode
will be processed even if @Size
from street1
fails: while SecondStep
is in the Total
group sequence and hence should not be triggered if FirstStep
has a failure, it also has been requested outside the sequence (in this case explicitly).
Note
|
If the group definition is invalid, a |
6.2. ConstraintViolation
ConstraintViolation
is the class describing a single constraint failure. A set of ConstraintViolation
is returned for an object validation.
ConstraintViolation
interface/**
* Describes a constraint violation. This object exposes the constraint
* violation context as well as the message describing the violation.
*
* @param <T> the type of the root bean
*
* @author Emmanuel Bernard
*/
public interface ConstraintViolation<T> {
/**
* @return the interpolated error message for this constraint violation
*/
String getMessage();
/**
* @return the non-interpolated error message for this constraint violation
*/
String getMessageTemplate();
/**
* Returns the root bean being validated. For method validation, returns
* the object the method is executed on.
* <p>
* Returns {@code null} when:
* <ul>
* <li>the {@code ConstraintViolation} is returned after calling
* {@link Validator#validateValue(Class, String, Object, Class[])}</li>
* <li>the {@code ConstraintViolation} is returned after validating a
* constructor.</li>
* </ul>
*
* @return the validated object, the object hosting the validated element or {@code null}
*/
T getRootBean();
/**
* Returns the class of the root bean being validated.
* For method validation, this is the object class the
* method is executed on.
* For constructor validation, this is the class the constructor
* is declared on.
*
* @return the class of the root bean or of the object hosting the validated element
*/
Class<T> getRootBeanClass();
/**
* Returns:
* <ul>
* <li>the bean instance the constraint is applied on if it is
* a bean constraint</li>
* <li>the bean instance hosting the property the constraint
* is applied on if it is a property constraint or a container element constraint
* hosted on a property</li>
* <li>{@code null} when the {@code ConstraintViolation} is returned
* after calling {@link Validator#validateValue(Class, String, Object, Class[])}
* </li>
* <li>the object the method is executed on if it is
* a method parameter, cross-parameter or return value constraint or a
* container element constraint hosted on a method parameter or return value</li>
* <li>{@code null} if it is a constructor parameter or
* cross-parameter constraint or a container element constraint hosted on a
* constructor parameter</li>
* <li>the object the constructor has created if it is a
* constructor return value constraint</li>
* </ul>
*
* @return the leaf bean
*/
Object getLeafBean();
/**
* Returns an {@code Object[]} representing the constructor or method invocation
* arguments if the {@code ConstraintViolation} is returned after validating the
* method or constructor parameters.
* Returns {@code null} otherwise.
*
* @return parameters of the method or constructor invocation or {@code null}
*
* @since 1.1
*/
Object[] getExecutableParameters();
/**
* Returns the return value of the constructor or method invocation
* if the {@code ConstraintViolation} is returned after validating the method
* or constructor return value.
* <p>
* Returns {@code null} if the method has no return value.
* Returns {@code null} otherwise.
*
* @return the method or constructor return value or {@code null}
*
* @since 1.1
*/
Object getExecutableReturnValue();
/**
* @return the property path to the value from {@code rootBean}
*/
Path getPropertyPath();
/**
* Returns the value failing to pass the constraint.
* For cross-parameter constraints, an {@code Object[]} representing
* the method invocation arguments is returned.
*
* @return the value failing to pass the constraint
*/
Object getInvalidValue();
/**
* Returns the constraint metadata reported to fail.
* The returned instance is immutable.
*
* @return constraint metadata
*/
ConstraintDescriptor<?> getConstraintDescriptor();
/**
* Returns an instance of the specified type allowing access to
* provider-specific APIs. If the Bean Validation provider
* implementation does not support the specified class,
* {@link ValidationException} is thrown.
*
* @param type the class of the object to be returned
* @param <U> the type of the object to be returned
* @return an instance of the specified class
* @throws ValidationException if the provider does not support the call
*
* @since 1.1
*/
<U> U unwrap(Class<U> type);
}
The getMessage()
method returns the interpolated (localized) message for the failing constraint (see Message interpolation for more information on message interpolator). This can be used by clients to expose user friendly messages.
The getMessageTemplate()
method returns the non-interpolated error message (usually the message
attribute on the constraint declaration). Frameworks can use this as an error code key.
The getRootBean()
method returns the root object being validated that led to the failing constraint (i.e. the object the client code passes to the Validator.validate()
method). For method validation, returns the object the method is executed on. For constructors or when Validator.validateValue()
is used, returns null
.
The getRootBeanClass()
method returns the class of the root bean being validated. For method validation, this is the object class the method is executed on. For constructor validation, this is the class the constructor is declared on.
The getLeafBean()
method returns the following object:
-
If a bean constraint, the bean instance the constraint is applied on.
-
If a property constraint or a container element constraint hosted on a property, the bean instance hosting the property the constraint is applied on.
-
If a property constraint,
null
when theConstraintViolation
is returned after callingValidator.validateValue()
. -
If a method parameter, cross-parameter or return value constraint or a container element constraint hosted on a method parameter or return value, the object the method is executed on.
-
If a constructor parameter or cross-parameter constraint or a container element constraint hosted on a constructor parameter,
null
. -
If a constructor return value constraint, the object the constructor has created.
The getExecutableParameters()
returns the parameters provided to the method or constructor invocation or null
if not validating a method or constructor parameters.
The getExecutableReturnValue()
returns the return value of the method or constructor invocation or null
if the method has no return value or if not validating a method or constructor return value.
The getInvalidValue()
method returns the value (field, property, method/constructor parameter, method/constructor return value, container element or validated object) being passed to isValid()
. For a cross-parameter constraint failure, an Object[]
representing the method/constructor invocation arguments is returned.
In case a constraint given on a container is subject to implicit application to the container element(s) (see Implicit unwrapping of containers), getInvalidValue()
returns the invalid container element value.
getConstraintDescriptor()
provides access to the failing constraint metadata (see ConstraintDescriptor).
The getPropertyPath()
method returns the Path
object representing the navigation path from the root object to the failing object.
unwrap()
is provided as a way to access objects of a given type specific to a Bean Validation provider typically as a complement to the ConstraintViolation
contract. Using this method makes your code non portable.
Path
and Node
interfaces and ElementKind
enum/**
* Represents the navigation path from an object to another
* in an object graph.
* Each path element is represented by a {@code Node}.
* <p>
* The path corresponds to the succession of nodes
* in the order they are returned by the {@code Iterator}.
*
* @author Emmanuel Bernard
* @author Gunnar Morling
* @author Guillaume Smet
*/
public interface Path extends Iterable<Path.Node> {
/**
* Returns a human-readable representation of this path.
* <p>
* Clients should not rely on any specific structure of the returned value. Instead they
* should iterate through the path nodes and obtain any required information by calling
* the methods on {@link Node} and its sub-types.
*
* @return a human-readable representation of this path
* @since 2.0
*/
@Override
String toString();
/**
* Represents an element of a navigation path.
*/
interface Node {
/**
* Returns the name of the element which the node represents:
* <ul>
* <li>{@code null} if it is a leaf node which represents an entity / bean.
* In particular, the node representing the root object.</li>
* <li>The property name for a property.</li>
* <li>The method name for a method.</li>
* <li>The unqualified name of the type declaring the constructor
* for a constructor.</li>
* <li>The parameter named as defined by the {@link ParameterNameProvider}
* for a method or constructor parameter.</li>
* <li>The literal {@code <cross-parameter>} for a method or constructor
* cross-parameter.</li>
* <li>The literal {@code <return value>} for a method or constructor return
* value.</li>
* <li>The node name as defined by the {@link ValueExtractor} for a container
* element; specifically, the literal {@code <list element>} for elements
* stored in a list, the literal {@code <iterable element>} for elements
* stored in an {@code Iterable}, the literal {@code <map key>} for the keys
* stored in a {@code Map} and the literal {@code <map value>} for the values
* stored in a {@code Map}.
* </ul>
*
* @return name of the element which the node represents
*/
String getName();
/**
* @return {@code true} if the node represents an object contained in
* a multi-valued container such as {@code Iterable} or {@code Map} or an array,
* {@code false} otherwise
*/
boolean isInIterable();
/**
* @return the index the node is placed in if contained in an array, a {@code List}
* or any other container supporting indexed access, {@code null} otherwise
*/
Integer getIndex();
/**
* @return the key the node is placed in if contained in a {@code Map} or any
* other container supporting keyed access, {@code null} otherwise
*/
Object getKey();
/**
* The kind of element represented by the node. The following relationship
* between an {@link ElementKind} and its {@code Node} subtype exists:
* <ul>
* <li>{@link ElementKind#BEAN}: {@link BeanNode}</li>
* <li>{@link ElementKind#PROPERTY}: {@link PropertyNode}</li>
* <li>{@link ElementKind#METHOD}: {@link MethodNode}</li>
* <li>{@link ElementKind#CONSTRUCTOR}: {@link ConstructorNode}</li>
* <li>{@link ElementKind#PARAMETER}: {@link ParameterNode}</li>
* <li>{@link ElementKind#CROSS_PARAMETER}: {@link CrossParameterNode}</li>
* <li>{@link ElementKind#RETURN_VALUE}: {@link ReturnValueNode}</li>
* <li>{@link ElementKind#CONTAINER_ELEMENT}: {@link ContainerElementNode}</li>
* </ul>
* <p>
* This is useful to narrow down the {@code Node} type and access node specific
* information:
* <pre>
* switch(node.getKind() {
* case METHOD:
* name = node.getName();
* params = node.as(MethodNode.class).getParameterTypes();
* case PARAMETER:
* index = node.as(ParameterNode.class).getParameterIndex();
* [...]
* }
* </pre>
* @return the {@code ElementKind}
*
* @since 1.1
*/
ElementKind getKind();
/**
* Narrows the type of this node down to the given type. The appropriate
* type should be checked before by calling {@link #getKind()}.
*
* @param <T> the type to narrow down to
* @param nodeType class object representing the descriptor type to narrow down to
* to
*
* @return this node narrowed down to the given type.
*
* @throws ClassCastException if this node is not assignable to the type {@code T}
* @since 1.1
*/
<T extends Node> T as(Class<T> nodeType);
/**
* Returns a human-readable representation of this node.
* <p>
* Clients should not rely on any specific structure of the returned value. Instead
* they should obtain any required information by calling the methods on this
* interface and its sub-types.
*
* @return a human-readable representation of this node
* @since 2.0
*/
@Override
String toString();
}
/**
* Node representing a method.
*
* @since 1.1
*/
interface MethodNode extends Node {
/**
* @return the list of parameter types
*/
List<Class<?>> getParameterTypes();
}
/**
* Node representing a constructor.
*
* @since 1.1
*/
interface ConstructorNode extends Node {
/**
* @return the list of parameter types
*/
List<Class<?>> getParameterTypes();
}
/**
* Node representing the return value of a method or constructor.
*
* @since 1.1
*/
interface ReturnValueNode extends Node {
}
/**
* Node representing a parameter of a method or constructor.
*
* @since 1.1
*/
interface ParameterNode extends Node {
/**
* @return the parameter index in the method or constructor definition
*/
int getParameterIndex();
}
/**
* Node representing the element holding cross-parameter constraints
* of a method or constructor.
*
* @since 1.1
*/
interface CrossParameterNode extends Node {
}
/**
* Node representing a bean.
*
* @since 1.1
*/
interface BeanNode extends Node {
/**
* @return the type of the container the node is placed in, if contained in a
* container type such as {@code Optional}, {@code List} or {@code Map},
* {@code null} otherwise
*
* @since 2.0
*/
Class<?> getContainerClass();
/**
* @return the index of the type argument affected by the violated constraint, if
* contained in a generic container type such as {@code Optional}, {@code List} or
* {@code Map}.
*
* @since 2.0
*/
Integer getTypeArgumentIndex();
}
/**
* Node representing a property.
*
* @since 1.1
*/
interface PropertyNode extends Node {
/**
* @return the type of the container the node is placed in, if contained in a
* container type such as {@code Optional}, {@code List} or {@code Map},
* {@code null} otherwise
*
* @since 2.0
*/
Class<?> getContainerClass();
/**
* @return the index of the type argument affected by the violated constraint, if
* contained in a generic container type such as {@code Optional}, {@code List} or
* {@code Map}, {@code null} otherwise
*
* @since 2.0
*/
Integer getTypeArgumentIndex();
}
/**
* Node representing an element in a generic container such as {@code Optional},
* {@code List} or {@code Map}.
*
* @since 2.0
*/
interface ContainerElementNode extends Node {
/**
* @return the type of the container the node is placed in
*/
Class<?> getContainerClass();
/**
* @return the index of the type argument affected by the violated constraint
*/
Integer getTypeArgumentIndex();
}
}
/**
* Enum of possible kinds of elements encountered in Bean Validation.
* <p>
* Mostly elements that can be constrained and described in the metadata
* but also elements that can be part of a {@link Path} and represented
* by a {@link Path.Node}
*
* @author Emmanuel Bernard
* @author Gunnar Morling
* @author Guillaume Smet
*
* @since 1.1
*/
public enum ElementKind {
/**
* A Java Bean or object.
*/
BEAN,
/**
* A property of a Java Bean.
*/
PROPERTY,
/**
* A method.
*/
METHOD,
/**
* A constructor.
*/
CONSTRUCTOR,
/**
* A parameter of a method or constructor.
*/
PARAMETER,
/**
* Element holding cross-parameter constraints of a method or constructor.
*/
CROSS_PARAMETER,
/**
* The return value of a method or constructor.
*/
RETURN_VALUE,
/**
* An element stored in a container, e.g. a key or value of a {@code Map} or an element
* of a {@code List}.
*
* @since 2.0
*/
CONTAINER_ELEMENT
}
Path
is an iterable of Node
objects. Node
offers the following methods:
-
getName()
returns the name of the element which the node represents:-
null
if it is a leaf node which represents an entity / bean. In particular, the node representing the root object. -
The property name for a property.
-
The method name for a method.
-
The unqualified name of the type declaring the constructor for a constructor.
-
The parameter named as defined by the
ParameterNameProvider
(see Naming parameters) for a method or constructor parameter. -
The literal
<cross-parameter>
for a method or constructor cross-parameter. -
The literal
<return value>
for a method or constructor return value. -
The name set by the applied value extractor for a container element constraint; specifically, when applying the default value extractor for iterable elements, list elements, map keys or map values, the literal
<iterable element>
,<list element>
,<map key>
or<map value>
, respectively.
-
-
isInIterable()
returnstrue
if the node represents an object contained in an array or in a multi-valued container such asIterable
orMap
,false
otherwise. -
getIndex()
returns the index of the node if it is contained in an array,List
or any other container supporting indexed access. Returnsnull
otherwise. -
getKey()
returns the key of the node if it is contained in aMap
or any other container supporting keyed access. Returnsnull
otherwise. -
getKind()
returns theElementKind
corresponding to the actual node type. This can be used in conjunction with the methodas()
to narrow the type and access node specific methods -
as(Class<? extends Node>)
returns the node instance narrowed to the type passed as a parameter or throws aClassCastException
if the type and node don’t match.
Nodes are of the following possible types:
-
BeanNode
-
PropertyNode
-
MethodNode
-
ConstructorNode
-
ParameterNode
-
CrossParameterNode
-
ReturnValueNode
-
ContainerElementNode
It is possible to narrow a node instance to its precise type and extract node specific information by the use of Node.getKind()
and Node.as(Class<? extends Node>)
.
In particular, MethodNode
and ConstructorNode
host getParameterTypes()
which return the method or constructor parameter list.
Likewise ParameterNode
hosts getParameterIndex()
which returns the parameter index in the method or constructor parameter list.
BeanNode
, PropertyNode
and ContainerElementNode
host getContainerClass()
and getTypeArgumentIndex()
.
If the node represents an element that is contained in a container such as Optional
, List
or Map
,
the former returns the declared type of the container and, if the container is of a generic type, the latter returns the index of the affected type argument.
Node node = [...];
switch ( node.getKind() ) {
case METHOD:
MethodNode methodNode = node.as(MethodNode.class);
methodName = methodNode.getName();
params = methodNode.getParameterTypes().toArray(
new Class<?>[methodNode.getParameterTypes().size()] );
break;
case CONSTRUCTOR:
ConstructorNode constructorNode = node.as(ConstructorNode.class);
methodName = constructorNode.getName();
params = constructorNode.getParameterTypes().toArray(
new Class<?>[constructorNode.getParameterTypes().size()] );
break;
case PARAMETER:
arg = node.as(ParameterNode.class).getParameterIndex();
break;
case CONTAINER_ELEMENT:
ContainerElementNode containerElementNode = node.as(ContainerElementNode.class);
containerClass = containerElementNode.getContainerClass();
typeArgumentIndex = containerElementNode.getTypeArgumentIndex();
break;
case CROSS_PARAMETER:
[...]
case RETURN_VALUE:
[...]
case PARAMETER:
[...]
case BEAN:
[...]
case PROPERTY:
[...]
}
Path
objects are built according to the following rules:
-
The runtime type is considered, not the static type. For example if a property is declared
Collection<String>
but its runtime type isArrayList<String>
, the property is considered anArrayList<String>
. -
If the failing object is the root object, a
BeanNode
with name set tonull
is added to thePath
. TheElementKind
of the node isElementKind.BEAN
. -
When an association is traversed:
-
a
PropertyNode
object whosename
equals the name of the association property (field name or Java Bean property name) is added toPath
. TheElementKind
of the node isElementKind.PROPERTY
. -
if the association is an array, a
List
or any other container whose value extractor invokesValueReceiver#indexedValue()
(see Value extractor definition), the followingNode
object added contains the index value ingetIndex()
-
if the association is a
Map
or any other container whose value extractor invokesValueReceiver#keyedValue()
, the followingNode
object added (representing a given map entry) contains the key value ingetKey()
-
for all
Iterable
,Map
or other container whose value extractor invokesValueReceiver#indexedValue()
,ValueReceiver#keyedValue()
orValueReceiver#iterableValue()
, the followingNode
object added is marked asinIterable
(isInIterable()
) -
if the traversed object is of a container type (e.g. a
List
orMap
), the followingNode
object added returns the declared type of the traversed container viagetContainerClass()
and the index of the affected type argument viagetTypeArgumentIndex()
-
-
When a nested container is traversed (e.g. when traversing into the elements of the lists in
Map<String, List<@Valid Address>>
):-
if the value extractor of the outer container has provided a non-null node name, a
ContainerElementNode
object whosename
equals that name is added toPath
. TheElementKind
of the node isElementKind.CONTAINER_ELEMENT
-
if the container is a
List
or any other container whose value extractor invokesValueReceiver#indexedValue()
, the followingNode
object added contains the index value ingetIndex()
-
if the container is a
Map
or any other container whose value extractor invokesValueReceiver#keyedValue()
, the followingNode
object added (representing a given map entry) contains the key value ingetKey()
-
for all
Iterable
,Map
or other container whose value extractor invokesValueReceiver#indexedValue()
,ValueReceiver#keyedValue()
orValueReceiver#iterableValue()
, the followingNode
object added is marked asinIterable
(isInIterable()
) -
the following
Node
object added returns the declared type of the traversed container viagetContainerClass()
and the index of the affected type argument viagetTypeArgumentIndex()
-
-
For a property level constraint (field and getter)
-
a
PropertyNode
object is added toPath
whosename
equals the name of the property (field name or Java Bean property name). TheElementKind
of the node isElementKind.PROPERTY
. -
the property path is considered complete
-
-
For a class level constraint:
-
a
BeanNode
object is added toPath
whosename
is null. TheElementKind
of the node isElementKind.BEAN
. -
the property path is considered complete
-
-
For a method/constructor constraint (parameter, cross-parameter or return value constraint on a method or constructor):
-
a
MethodNode
respectively aConstructorNode
object is added to thePath
which represents the validated method respectively constructor. Thename
of the node equals the validated method name or the validated constructor’s unqualified class name, theElementKind
of the node isElementKind.METHOD
respectivelyElementKind.CONSTRUCTOR
. -
if the constraint is on a parameter, a
ParameterNode
object is added to thePath
which represents the validated parameter. Thename
of the node equals the parameter name as determined by the current parameter name provider (see Naming parameters). TheElementKind
of the node isElementKind.PARAMETER
. -
if the constraint is a cross-parameter constraint, a
CrossParameterNode
object is added to thePath
which represents the validated cross-parameter element. Thename
of the node has the constant value<cross-parameter>
. TheElementKind
of the node isElementKind.CROSS_PARAMETER.
-
if the constraint is on the return value, a
ReturnValueNode
object is added to thePath
which represents the validated return value. Thename
of the node has the constant value<return value>
. TheElementKind
of the node isElementKind.RETURN_VALUE.
-
the property path is considered complete
-
-
If a parameter or the return value of a method or constructor is traversed:
-
a
MethodNode
respectivelyConstructorNode
object is added to thePath
which represents the concerned method respectively constructor. Thename
of the node equals the concerned method name or the constructor’s unqualified class name, theElementKind
of the node isElementKind.METHOD
orElementKind.CONSTRUCTOR
, respectively. -
if a parameter is traversed, a
ParameterNode
object is added to thePath
which represents the traversed parameter. Thename
of the node equals the parameter name as determined by the current parameter name provider. TheElementKind
of the node isElementKind.PARAMETER
. -
if a return value is traversed, a
ReturnValueNode
object is added to thePath
which represents the traversed return value. Thename
of the node has the constant value<return value>
. TheElementKind
of the node isElementKind.RETURN_VALUE.
-
if the parameter/return value is a
List
or an array, the followingNode
object added contains the index value ingetIndex()
. -
if the parameter/return value is a
Map
, the followingNode
object added (representing a given map entry) contains the key value ingetKey()
. -
for all
Iterable
orMap
, the followingNode
object added is marked asinIterable
(isInIterable()
).
-
-
For a container element constraint:
-
if the corresponding value extractor (see Value extractor definition) has specified a node name when calling one of the receiver methods, a
ContainerElementNode
object with that name is added to thePath
. TheElementKind
of the node isElementKind.CONTAINER_ELEMENT
.getContainerClass()
returns the declared type of the container hosting the constraint.getTypeArgumentIndex()
returns the index of the type argument hosting the constraint. If the constraint is given on a container and is subject to implicit application to the container’s element(s) (see Implicit unwrapping of containers) and the applied value extractor is not tied to a type parameter,getTypeArgumentIndex()
returns null. -
if the corresponding value extractor has passed no node name to the called receiver method, no node is appended.
-
the property path is considered complete
-
If additional path nodes are added in a constraint validator implementation using the node builder API (see Constraint validation implementation), the following rules apply:
-
if the default path ends with a
BeanNode
, this node is removed and the first added node (aPropertyNode
) inherits itsinIterable
,key
andindex
values.inIterable
,key
andindex
value must not be specified directly on this first node by the user. -
if the default path ends with a
CrossParameterNode
, this node is removed. -
then the additional nodes are appended to the (possibly amended) path generated by the Bean Validation engine as previously described:
-
A
PropertyNode
is appended in caseaddPropertyNode(String)
is invoked. The node name is equal to the name provided. TheElementKind
of the node isElementKind.PROPERTY
. -
A
BeanNode
is appended in caseaddBeanNode()
is invoked. The node name isnull
. TheElementKind
of the node isElementKind.BEAN
. -
A
ParameterNode
is appended in caseaddParameterNode(int)
is invoked. The node name is equal to the parameter name at the provided index. The name is determined by the current parameter name provider. TheElementKind
of the node isElementKind.PARAMETER
. The previous node (removed) must be aCrossParameterNode
. -
A
ContainerElementNode
is appended in caseaddContainerElementNode(String, Class, Integer)
is invoked. The name, container type and type argument index of the node are equal to the values provided. TheElementKind
of the node isElementKind.CONTAINER_ELEMENT
. -
If
inIterable()
is invoked, the node returnstrue
forisInIterable()
,false
otherwise. -
If
inContainer(Class, Integer)
is invoked, the node returns the passed container type and type argument index fromgetContainerClass()
andgetTypeArgumentIndex()
, respectively. -
If
atIndex(Integer)
is invoked, the node returns the provided integer forgetIndex()
,null
otherwise. -
If
atKey(Object)
is invoked, the node returns the provided object forgetKey()
,null
otherwise.
Note
|
A given |
Note
|
From |
Note
|
|
Let there be the following object definitions:
@SecurityChecking
public class Author {
private String firstName;
@NonEmpty(message="lastname must not be null")
private String lastName;
@Size(max=30)
private String company;
[...]
@OldAndNewPasswordsDifferent
@NewPasswordsIdentical
public void renewPassword(
String oldPassword, String newPassword, String retypedNewPassword) {
[...]
}
}
@AvailableInStore(groups={Availability.class})
public class Book {
@NonEmpty(groups={FirstLevelCheck.class, Default.class})
private String title;
@Valid
@NotNull
private List<Author> authors;
@Valid
private Map<String, Review> reviewsPerSource;
@Valid
private Review pickedReview;
private List<@NotBlank String> tags;
private Map<Integer, List<@NotBlank String>> tagsByChapter;
private List<@Valid Category> categories;
private Map<Integer, List<@Valid Author>> authorsByChapter;
[...]
}
public class Review {
@Min(0)
private int rating;
[...]
}
public class Category {
@Size(min=3)
private String name;
// [...]
}
public class Library {
public Library(@NotNull String name, @NotNull String location) {
[...]
}
public void addBook(@NotNull @Valid Book book) {
[...]
}
public void addAllBooks(@NotNull List<@Valid Book> books) {
[...]
}
@NotNull public String getLocation() {
[...]
}
public Map<Author, @Valid Book> getMostPopularBookPerAuthor() {
[...]
}
}
Assuming a Book
instance gets validated, the property paths to the different constraints would be as described in propertyPath examples:
Constraint | propertyPath |
---|---|
|
BeanNode(name=null, inIterable=false, index=null, key=null, containerClass=null, typeArgumentIndex=null, kind=ElementKind.BEAN) |
|
PropertyNode(name=title, inIterable=false, index=null, key=null, containerClass=null, typeArgumentIndex=null, kind=ElementKind.PROPERTY) |
|
PropertyNode(name=authors, inIterable=false, index=null, key=null, containerClass=null, typeArgumentIndex=null, kind=ElementKind.PROPERTY) |
|
PropertyNode(name=authors, inIterable=false, index=null, key=null, containerClass=null, typeArgumentIndex=null, kind=ElementKind.PROPERTY) BeanNode(name=null, inIterable=true, index=3, key=null, containerClass=List.class, typeArgumentIndex=0, kind=ElementKind.BEAN) |
|
PropertyNode(name=authors, inIterable=false, index=null, key=null, containerClass=null, typeArgumentIndex=null, kind=ElementKind.PROPERTY) PropertyNode(name=lastName, inIterable=true, index=3, key=null, containerClass=List.class, typeArgumentIndex=0, kind=ElementKind.PROPERTY) |
|
PropertyNode(name=authors, inIterable=false, index=null, key=null, containerClass=null, typeArgumentIndex=null, kind=ElementKind.PROPERTY) PropertyNode(name=company, inIterable=true, index=0, key=null, containerClass=List.class, typeArgumentIndex=0, kind=ElementKind.PROPERTY) |
|
PropertyNode(name=reviewsPerSource, inIterable=false, index=null, key=null, containerClass=null, typeArgumentIndex=null, kind=ElementKind.PROPERTY) PropertyNode(name=rating, inIterable=true, index=null, key="Consumer Report", containerClass=Map.class, typeArgumentIndex=1, kind=ElementKind.PROPERTY) |
|
PropertyNode(name=pickedReview, inIterable=false, index=null, key=null, containerClass=null, typeArgumentIndex=null, kind=ElementKind.PROPERTY) PropertyNode(name=rating, inIterable=false, index=null, key=null, containerClass=null, typeArgumentIndex=null, kind=ElementKind.PROPERTY) |
|
PropertyNode(name=tags, inIterable=false, index=null, key=null, containerClass=null, typeArgumentIndex=null, kind=ElementKind.PROPERTY) ContainerElementNode(name=<list element>, inIterable=true, index=1, key=null, containerClass=List.class, typeArgumentIndex=0, kind=ElementKind.CONTAINER_ELEMENT) |
|
PropertyNode(name=tagsByChapter, inIterable=false, index=null, key=null, containerClass=null, typeArgumentIndex=null, kind=ElementKind.PROPERTY) ContainerElementNode(name=<map value>, inIterable=true, index=null, key=4, containerClass=Map.class, typeArgumentIndex=1, kind=ElementKind.CONTAINER_ELEMENT) ContainerElementNode(name=<list element>, inIterable=true, index=2, key=null, containerClass=List.class, typeArgumentIndex=0, kind=ElementKind.CONTAINER_ELEMENT) |
|
PropertyNode(name=categories, inIterable=false, index=null, key=null, containerClass=null, typeArgumentIndex=null, kind=ElementKind.PROPERTY) PropertyNode(name=name, inIterable=true, index=1, key=null, containerClass=List.class, typeArgumentIndex=0, kind=ElementKind.PROPERTY) |
|
PropertyNode(name=authorsByChapter, inIterable=false, index=null, key=null, containerClass=null, typeArgumentIndex=null, kind=ElementKind.PROPERTY) ContainerElementNode(name=<map value>, inIterable=true, index=null, key=4, containerClass=Map.class, typeArgumentIndex=1, kind=ElementKind.CONTAINER_ELEMENT) PropertyNode(name=lastName, inIterable=true, index=2, key=null, containerClass=List.class, typeArgumentIndex=0, kind=ElementKind.PROPERTY) |
Assuming the constructor and methods of the Library
class are subject to method constraint validation and parameter names can be obtained for them, the following property paths would exist for the different constraints:
Constraint | propertyPath |
---|---|
|
ConstructorNode(name=Library, inIterable=false, index=null, key=null, kind=ElementKind.CONSTRUCTOR, parameterTypes=[String.class,String.class]) ParameterNode(name=location, inIterable=false, index=null, key=null, kind=ElementKind.PARAMETER, parameterIndex=1) |
|
MethodNode(name=addBook, inIterable=false, index=null, key=null, kind=ElementKind.METHOD, parameterTypes=[Book.class]) ParameterNode(name=book, inIterable=false, index=null, key=null, kind=ElementKind.PARAMETER, parameterIndex=0) |
|
MethodNode(name=addBook, inIterable=false, index=null, key=null, kind=ElementKind.METHOD, parameterTypes=[Book.class]) ParameterNode(name=book, inIterable=false, index=null, key=null, kind=ElementKind.PARAMETER, parameterIndex=0) PropertyNode(name=title, inIterable=false, index=null, key=null, containerClass=null, typeArgumentIndex=null, kind=ElementKind.PROPERTY) |
|
MethodNode(name=addAllBooks, inIterable=false, index=null, key=null, kind=ElementKind.METHOD, parameterTypes=[List.class]) ParameterNode(name=books, inIterable=false, index=null, key=null, kind=ElementKind.PARAMETER, parameterIndex=0) PropertyNode(name=title, inIterable=true, index=3, key=null, containerClass=List.class, typeArgumentIndex=0, kind=ElementKind.PROPERTY) |
|
MethodNode(name=getLocation, inIterable=false, index=null, key=null, kind=ElementKind.METHOD, parameterTypes=[]) ReturnValueNode(name=<return value>, inIterable=false, index=null, key=null, kind=ElementKind.RETURN_VALUE) |
|
MethodNode(name=getMostPopularBookPerAuthor, inIterable=false, index=null, key=null, kind=ElementKind.METHOD, parameterTypes=[]) ReturnValueNode(name=<return value>, inIterable=false, index=null, key=null, kind=ElementKind.RETURN_VALUE) PropertyNode(name=title, inIterable=true, index=null, key=Author(firstName=John, lastName=Doe), containerClass=Map.class, typeArgumentIndex=1, kind=ElementKind.PROPERTY) |
|
MethodNode(name=renewPassword, inIterable=false, index=null, key=null, kind=ElementKind.METHOD, parameterTypes=[String.class, String.class, String.class]) CrossParameterNode(name=<cross-parameter>, inIterable=false, index=null, key=null, kind=ElementKind.CROSS_PARAMETER) |
|
MethodNode(name=renewPassword, inIterable=false, index=null, key=null, kind=ElementKind.METHOD, parameterTypes=[String.class, String.class, String.class]) ParameterNode(name=retypedNewPassword, inIterable=false, index=null, key=null, kind=ElementKind.PARAMETER, parameterIndex=2) |
Note
|
Bean Validation implementations should ensure that a If a user wishes to send |
6.2.1. Examples
These examples assume the following definition of @NonEmpty
:
package com.acme.constraint;
@Documented
@NotNull
@Size(min = 1)
@ReportAsSingleViolation
@Constraint(validatedBy = NonEmpty.NonEmptyValidator.class)
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
public @interface NonEmpty {
String message() default "{com.acme.constraint.NonEmpty.message}";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
NonEmpty[] value();
}
class NonEmptyValidator implements ConstraintValidator<NonEmpty, String> {
@Override
public boolean isValid(String value, ConstraintValidatorContext context) {
return true;
}
}
}
And the following class definitions:
public class Author {
private String firstName;
@NonEmpty(message = "lastname must not be null")
private String lastName;
@Size(max = 30)
private String company;
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String getCompany() {
return company;
}
public void setCompany(String company) {
this.company = company;
}
}
public class Book {
@NonEmpty(groups = { FirstLevelCheck.class, Default.class })
private String title;
@Valid
@NotNull
private Author author;
private List<@Size(min=3, max=30) String> tags;
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public Author getAuthor() {
return author;
}
public void setAuthor(Author author) {
this.author = author;
}
public List<String> getTags() {
return tags;
}
public void setTags(List<String> tags) {
this.tags = tags;
}
}
When executing the following validation:
Author author = new Author();
author.setCompany( "ACME" );
List<String> tags = Arrays.asList( "a", "science fiction" );
Book book = new Book();
book.setTitle( "" );
book.setAuthor( author );
book.setTags( tags );
Validator validator = Validation.buildDefaultValidatorFactory().getValidator();
Set<ConstraintViolation<Book>> constraintViolations = validator.validate( book );
Then constraintViolations
is a set of size 3. One of the entries represents the failure of @NonEmpty
(or more precisely @Size(min=1)
a composing constraint of @NonEmpty
) on the title
property.
The ConstraintViolation
object for this failure passes the following assertions:
ContraintViolation
for title
//assuming an english locale, the interpolated message is returned
assert "may not be null or empty".equals( constraintViolation.getMessage() );
assert book == constraintViolation.getRootBean();
assert book == constraintViolation.getLeafBean();
//the offending value
assert book.getTitle().equals( constraintViolation.getInvalidValue() );
//the offending property
Iterator<Node> nodeIter = constraintViolation.getPropertyPath().iterator();
Node node = nodeIter.next();
assert "title".equals( node.getName() );
assert ElementKind.PROPERTY.equals( node.getKind() );
assert false == nodeIter.hasNext();
The second failure, @NonEmpty
(or more precisely @NotNull
a composing constraint of @NonEmpty
) on the author’s lastname
, will produce the ConstraintViolation
object satisfying the following assertions:
ContraintViolation
for lastName
assert "lastname must not be null".equals( constraintViolation.getMessage() );
assert book == constraintViolation.getRootBean();
assert author == constraintViolation.getLeafBean();
//the offending value
assert book.getAuthor().getLastName() == constraintViolation.getInvalidValue();
//the offending property
Iterator<Node> nodeIter = constraintViolation.getPropertyPath().iterator();
Node node = nodeIter.next();
assert "author".equals( node.getName() );
assert ElementKind.PROPERTY.equals( node.getKind() );
node = nodeIter.next();
assert "lastName".equals( node.getName() );
assert ElementKind.PROPERTY.equals( node.getKind() );
assert false == nodeIter.hasNext();
The third failure, @Size
on one of the book’s tags
, will produce a ConstraintViolation
object satisfying the following assertions:
ContraintViolation
for tags
assert "size must be between 3 and 30".equals( constraintViolation.getMessage() );
assert book == constraintViolation.getRootBean();
assert book == constraintViolation.getLeafBean();
//the offending value
assert book.getTags().get( 0 ) == constraintViolation.getInvalidValue();
//the offending property
Iterator<Node> nodeIter = constraintViolation.getPropertyPath().iterator();
Node node = nodeIter.next();
assert "tags".equals( node.getName() );
assert ElementKind.PROPERTY.equals( node.getKind() );
node = nodeIter.next();
assert "<list element>".equals( node.getName() );
assert ElementKind.CONTAINER_ELEMENT.equals( node.getKind() );
assert false == nodeIter.hasNext();
6.2.2. Examples for method and constructor constraint violations
The following examples assume the constraint, class and object definitions given in the previous section. Additionally the following class and object definitions are assumed:
public class Library {
@PublicLibrary
public Library() {
[...]
}
public Library(@NotNull List<@Valid Book> books) {
[...]
}
public void addBook(@NotNull @Valid Book book) {
[...]
}
@Valid public Map<Author, Book> getMostPopularBookPerAuthor() {
[...]
}
}
public class User {
@OldAndNewPasswordsDifferent
public void renewPassword(String oldPassword, String newPassword, String retypedNewPassword);
}
Library library = new Library();
author.setLastName("Doe");
Assuming the following invocation of addBook()
is subject to method parameter validation:
library.addBook(null);
Then one ConstraintViolation
object would be returned by ExecutableValidator.validateParameters()
which satisfies the following assertions:
//assuming an english locale, the interpolated message is returned
assert "must not be null".equals( constraintViolation.getMessage() );
assert library == constraintViolation.getRootBean();
assert Library.class == constraintViolation.getRootBeanClass();
assert library == constraintViolation.getLeafBean();
assert null == constraintViolation.getInvalidValue();
assert new Object[]{ null }.equals( constraintViolation.getExecutableParameters() );
assert null == constraintViolation.getExecutableReturnValue();
Iterator<Node> nodeIter = constraintViolation.getPropertyPath().iterator();
Node node = nodeIter.next();
assert "addBook".equals( node.getName() );
assert ElementKind.METHOD.equals( node.getKind() );
node = nodeIter.next();
//assuming the default parameter name provider is used and parameter names can
//be obtained
assert "book".equals( node.getName() );
assert ElementKind.PARAMETER.equals( node.getKind() );
assert false == nodeIter.hasNext();
Assuming the following invocation of addBook()
is subject to method parameter validation:
library.addBook(book);
Then one ConstraintViolation
object would be returned by ExecutableValidator.validateParameters()
which satisfies the following assertions:
//assuming an english locale, the interpolated message is returned
assert "may not be null or empty".equals( constraintViolation.getMessage() );
assert library == constraintViolation.getRootBean();
assert Library.class == constraintViolation.getRootBeanClass();
assert book == constraintViolation.getLeafBean();
assert book.getTitle().equals( constraintViolation.getInvalidValue() );
assert new Object[]{ book }.equals( constraintViolation.getExecutableParameters() );
assert null == constraintViolation.getExecutableReturnValue();
Iterator<Node> nodeIter = constraintViolation.getPropertyPath().iterator();
Node node = nodeIter.next();
assert "addBook".equals( node.getName() );
assert ElementKind.METHOD.equals( node.getKind() );
node = nodeIter.next();
//assuming the default parameter name provider is used and parameter names can
//be obtained
assert "book".equals( node.getName() );
assert ElementKind.PARAMETER.equals( node.getKind() );
node = nodeIter.next();
assert "title".equals( node.getName() );
assert ElementKind.PROPERTY.equals( node.getKind() );
assert false == nodeIter.hasNext();
Assuming the following invocation of User.renewPassword()
is subject to method parameter validation and the @OldAndNewPasswordsDifferent
constraint is violated:
User user = [...];
user.renewPassword("foo", "foo", "foo");
Then one ConstraintViolation
object would be returned by ExecutableValidator.validateParameters()
which satisfies the following assertions:
assert user == constraintViolation.getRootBean();
assert User.class == constraintViolation.getRootBeanClass();
assert user == getLeafBean();
assert new Object[]{ "foo", "foo", "foo" }.equals( constraintViolation.getInvalidValue() );
assert new Object[]{ "foo", "foo", "foo" }.equals( constraintViolation.getExecutableParameters() );
assert null == constraintViolation.getExecutableReturnValue();
Iterator<Node> nodeIter = constraintViolation.getPropertyPath().iterator();
Node node = nodeIter.next();
assert "renewPassword".equals( node.getName() );
assert ElementKind.METHOD.equals( node.getKind() );
node = nodeIter.next();
assert "<cross-parameter>" == node.getName();
assert ElementKind.CROSS_PARAMETER.equals( node.getKind() );
assert false == nodeIter.hasNext();
Assuming the following invocation of the Library
constructor accepting a list of books is subject to constructor parameter validation:
Library anotherLibrary = new Library(null);
Then one ConstraintViolation
object would be returned by ExecutableValidator.validateConstructorParameters()
which satisfies the following assertions:
//assuming an english locale, the interpolated message is returned
assert "must not be null".equals( constraintViolation.getMessage() );
assert null == constraintViolation.getRootBean();
assert Library.class == constraintViolation.getRootBeanClass();
assert null == constraintViolation.getLeafBean();
assert null == constraintViolation.getInvalidValue();
assert new Object[]{ null }.equals( constraintViolation.getExecutableParameters() );
assert null == constraintViolation.getExecutableReturnValue();
Iterator<Node> nodeIter = constraintViolation.getPropertyPath().iterator();
Node node = nodeIter.next();
assert "Library".equals( node.getName() );
assert ElementKind.CONSTRUCTOR.equals( node.getKind() );
node = nodeIter.next();
//assuming the default parameter name provider is used and parameter names can
//be obtained
assert "books".equals( node.getName() );
assert ElementKind.PARAMETER.equals( node.getKind() );
assert false == nodeIter.hasNext();
Assuming the following invocation of getMostPopularBookPerAuthor()
is subject to method return value validation and returns a Map
containing one entry with key author
and value book
:
Map<Author, Book> mostPopularBookPerAuthor = library.getMostPopularBookPerAuthor();
Then one ConstraintViolation
object would be returned by ExecutableValidator.validateReturnValue()
which satisfies the following assertions:
//assuming an english locale, the interpolated message is returned
assert "may not be null or empty".equals( constraintViolation.getMessage() );
assert library == constraintViolation.getRootBean();
assert Library.class == constraintViolation.getRootBeanClass();
assert book == constraintViolation.getLeafBean();
assert book.getTitle().equals( constraintViolation.getInvalidValue() );
assert null == constraintViolation.getExecutableParameters();
assert mostPopularBookPerAuthor == constraintViolation.getExecutableReturnValue();
Iterator<Node> nodeIter = constraintViolation.getPropertyPath().iterator();
Node node = nodeIter.next();
assert "getMostPopularBookPerAuthor".equals( node.getName() );
assert ElementKind.METHOD.equals( node.getKind() );
node = nodeIter.next();
assert "<return value>" == node.getName();
assert ElementKind.RETURN_VALUE.equals( node.getKind() );
node = nodeIter.next();
assert "title".equals( node.getName() );
assert ElementKind.PROPERTY.equals( node.getKind() );
assert author.equals( node.getKey() );
assert true == node.isInIterable();
assert false == nodeIter.hasNext();
Assuming the following invocation of the Library
default constructor is subject to constructor return value validation and returns an instance which violates the @PublicLibrary
constraint:
Library publicLibrary = new Library();
Then one ConstraintViolation
object would be returned by ExecutableValidator.validateConstructorReturnValue()
which satisfies the following assertions:
assert null == constraintViolation.getRootBean();
assert Library.class == constraintViolation.getRootBeanClass();
assert publicLibrary == constraintViolation.getLeafBean();
assert publicLibrary == constraintViolation.getInvalidValue();
assert null == constraintViolation.getExecutableParameters();
assert library == constraintViolation.getExecutableReturnValue();
Iterator<Node> nodeIter = constraintViolation.getPropertyPath().iterator();
Node node = nodeIter.next();
assert "Library".equals( node.getName() );
assert ElementKind.CONSTRUCTOR.equals( node.getKind() );
node = nodeIter.next();
assert "<return value>" == node.getName();
assert ElementKind.RETURN_VALUE.equals( node.getKind() );
assert false == nodeIter.hasNext();
6.3. Message interpolation
A message interpolator is responsible for transforming the so called message descriptor specified via the message attribute of the constraint into a fully expanded, human-readable error message.
6.3.1. Default message interpolation
Every conforming Bean Validation implementation includes a default message interpolator which has to comply with the algorithm defined here to interpolate message descriptors. As precondition for message interpolation the following applies:
-
Each constraint defines a message descriptor via its
message
property. -
Every constraint definition defines a default message descriptor for that constraint.
-
Messages can be overridden at constraint declaration time by setting the
message
property on the constraint.
The message descriptor is a string literal and may contain one or more message parameters or expressions. Message parameters and expressions are string literals enclosed in {}
or ${}
respectively. The following character escaping rules apply:
-
\{
is considered as the literal{
instead of being considered as the beginning of a message parameter -
\}
is considered as the literal}
instead of being considered as the end of a message parameter -
\\
is considered as the literal\
instead of being considered as the escaping character -
\$
is considered as the literal$
instead of being considered as the beginning of a message expression
Below are two examples using message parameters and expressions. The second is evaluated using Expression Language as defined in Message expressions using Expression Language (EL).
Value must be between {min} and {max}
Must be greater than ${inclusive == true ? 'or equal to ' : ''}{value}
6.3.1.1. Default message interpolation algorithm
The default message interpolator uses the following steps:
-
Message parameters are extracted from the message string and used as keys to search the
ResourceBundle
namedValidationMessages
(often materialized as the property file/ValidationMessages.properties
and its locale variations) using the defined locale (see Locale for default message interpolation). If a property is found, the message parameter is replaced with the property value in the message string. Step 1 is applied recursively until no replacement is performed (i.e. a message parameter value can itself contain a message parameter). -
Message parameters are extracted from the message string and used as keys to search the Bean Validation provider’s built-in
ResourceBundle
using the defined locale (see Locale for default message interpolation). If a property is found, the message parameter is replaced with the property value in the message string. Contrary to step 1, step 2 is not processed recursively. -
If step 2 triggers a replacement, then step 1 is applied again. Otherwise step 4 is performed.
-
Message parameters are extracted from the message string. Those matching the name of an attribute of the constraint are replaced by the value of that attribute in the constraint declaration. Parameter interpolation has precedence over message expressions. For example for the message descriptor
${value}
, trying to evaluate{value}
as message parameter has precedence over evaluating${value}
as message expression. -
Message expressions are extracted from the message string and evaluated using Expression Language. See also Message expressions using Expression Language (EL).
Note
|
The proposed algorithm ensures that custom resource bundle always have priority over built-in resource bundle at all level of the recursive resolution. It also ensures that constraint declarations attributes values are not interpolated further. |
Note
|
The precedence of message parameter over expression interpolation ensures backwards compatibility to Bean Validation 1.0. |
6.3.1.2. Locale for default message interpolation
The locale to be used for message interpolation is defined as following:
-
if the locale is passed explicitly to the interpolator method via
interpolate(String, Context, Locale)
, this provided instance is used. -
otherwise, the default
Locale
as provided byLocale.getDefault()
is used.
6.3.1.3. Message expressions using Expression Language (EL)
The default message interpolation allows the use of Expression Language (EL) as defined in JSR 341. Expressions to be evaluated by EL need to be enclosed in ${}
within the message descriptor . The following properties and beans have to be made available in the EL context:
-
the attribute values of the constraint declaration mapped to their attribute name
-
the validated value mapped under the name
validatedValue
. -
a bean mapped to the name
formatter
exposing the vararg methodformat(String format, Object... args)
. This method must behave likejava.util.Formatter.format(String format, Object... args)
. The locale used for formatting is defined by Locale for default message interpolation. Theformatter
bean allows to format property values, for example in the case of the validated value being 98.12345678,${formatter.format('%1$.2f', validatedValue)}
would format it to 98.12 (two digits after the decimal point, where the use of '.' vs ',' would be locale specific).
If an exception occurs during message interpolation, e.g. due to invalid expressions or references to an unknown property, the message expression stays unchanged.
6.3.2. Custom message interpolation
A custom message interpolator may be provided (e.g., to interpolate contextual data, or to adjust the default Locale
used). A message interpolator implements the MessageInterpolator
interface.
MessageInterpolator
interface/**
* Interpolates a given constraint violation message.
* <p>
* Implementations should be as tolerant as possible on syntax errors.
* Implementations must be thread-safe.
*
* @author Emmanuel Bernard
* @author Hardy Ferentschik
*/
public interface MessageInterpolator {
/**
* Interpolates the message template based on the constraint validation context.
* <p>
* The locale is defaulted according to the {@code MessageInterpolator}
* implementation. See the implementation documentation for more detail.
*
* @param messageTemplate the message to interpolate
* @param context contextual information related to the interpolation
*
* @return interpolated error message
*/
String interpolate(String messageTemplate, Context context);
/**
* Interpolates the message template based on the constraint validation context.
* The {@code Locale} used is provided as a parameter.
*
* @param messageTemplate the message to interpolate
* @param context contextual information related to the interpolation
* @param locale the locale targeted for the message
*
* @return interpolated error message
*/
String interpolate(String messageTemplate, Context context, Locale locale);
/**
* Information related to the interpolation context.
*/
interface Context {
/**
* @return {@link ConstraintDescriptor} corresponding to the constraint being
* validated
*/
ConstraintDescriptor<?> getConstraintDescriptor();
/**
* @return value being validated
*/
Object getValidatedValue();
/**
* Returns an instance of the specified type allowing access to
* provider-specific APIs. If the Bean Validation provider
* implementation does not support the specified class,
* {@link ValidationException} is thrown.
*
* @param type the class of the object to be returned
* @param <T> the type of the object to be returned
* @return an instance of the specified class
* @throws ValidationException if the provider does not support the call
*
* @since 1.1
*/
<T> T unwrap(Class<T> type);
}
}
messageTemplate
is the value of the message
attribute of the constraint declaration or provided to the ConstraintValidatorContext
methods.
The Context
object contains contextual information related to the interpolation.
getConstraintDescriptor()
returns the ConstraintDescriptor
object representing the metadata of the failing constraint (see Constraint metadata request APIs).
getValidatedValue()
returns the value being validated.
MessageInterpolator.interpolate(String, Context)
is invoked for each constraint violation report generated. The default Locale
of custom message interpolators is implementation specific.
MessageInterpolator.interpolate(String, Context, Locale)
can be invoked by a wrapping MessageInterpolator
to enforce a specific Locale
value by bypassing or overriding the default Locale
strategy (see Use MessageInterpolator to use a specific Locale value).
A message interpolator implementation must be thread-safe.
The message interpolator is provided to the ValidatorFactory
at construction time using Configuration.messageInterpolator(MessageInterpolator)
. This message interpolator is shared by all Validator
objects generated by this ValidatorFactory
.
It is possible to override the MessageInterpolator
implementation for a given Validator
instance by invoking ValidatorFactory.usingContext().messageInterpolator(messageInterpolator).getValidator()
.
It is recommended that MessageInterpolator
implementations delegate final interpolation to the Bean Validation default MessageInterpolator
to ensure standard Bean Validation interpolation rules are followed, The default implementation is accessible through Configuration.getDefaultMessageInterpolator()
.
If the interpolation process leads to an exception, the exception is wrapped into a ValidationException
.
6.3.3. Examples
These examples describe message interpolation based on the default message interpolator’s built-in messages (see Standard ResourceBundle messages), and the ValidationMessages.properties
file shown in table message interpolation. The current locale is assumed English.
//ValidationMessages.properties
myapp.creditcard.error=credit card number not valid
Failing constraint declaration |
interpolated message |
|
must not be null |
|
must be less than or equal to 30 |
|
Key must have {5} \ {15} characters |
|
numeric value out of bounds (<9 digits>.<2 digits> expected) |
|
credit card number not valid |
Here is an approach to specify the Locale
value to choose on a given Validator
using a Locale
aware MessageInterpolator
. See Bootstrapping for more details on the APIs.
/**
* Delegates to a MessageInterpolator implementation but enforces a given Locale
*/
public class LocaleSpecificMessageInterpolator implements MessageInterpolator {
private final MessageInterpolator defaultInterpolator;
private final Locale defaultLocale;
public LocaleSpecificMessageInterpolator(MessageInterpolator interpolator, Locale locale) {
this.defaultLocale = locale;
this.defaultInterpolator = interpolator;
}
/**
* enforces the locale passed to the interpolator
*/
@Override
public String interpolate(String message,
Context context) {
return defaultInterpolator.interpolate(message,
context,
this.defaultLocale);
}
// no real use, implemented for completeness
@Override
public String interpolate(String message,
Context context,
Locale locale) {
return defaultInterpolator.interpolate(message, context, locale);
}
}
Locale locale = getMyCurrentLocale();
MessageInterpolator interpolator = new LocaleSpecificMessageInterpolator(
validatorFactory.getMessageInterpolator(),
locale);
Validator validator = validatorFactory.usingContext()
.messageInterpolator(interpolator)
.getValidator();
Most of the time, however, the relevant Locale
will be provided by your application framework transparently. This framework will implement its own version of MessageInterpolator
and pass it during the ValidatorFactory
configuration. The application will not have to set the Locale
itself. This example shows how a container framework would implement MessageInterpolator
to provide a user specific default locale.
MessageInterpolator
implementationpublic class ContextualMessageInterpolator implements MessageInterpolator {
private final MessageInterpolator delegate;
public ContextualMessageInterpolator(MessageInterpolator delegate) {
this.delegate = delegate;
}
@Override
public String interpolate(String message, Context context) {
Locale locale = Container.getManager().getUserLocale();
return this.delegate.interpolate(
message, context, locale );
}
@Override
public String interpolate(String message, Context context, Locale locale) {
return this.delegate.interpolate(message, context, locale);
}
}
//Build the ValidatorFactory
Configuration<?> configuration = Validation.byDefaultProvider().configure();
ValidatorFactory factory = configuration
.messageInterpolator(
new ContextualMessageInterpolator(
configuration.getDefaultMessageInterpolator() ) )
.buildValidatorFactory();
//The container uses the factory to validate constraints using the specific MessageInterpolator
Validator validator = factory.getValidator();
6.4. Triggering method validation
Bean Validation itself doesn’t trigger the evaluation of method constraints. That is, just annotating any methods or constructors with parameter or return value constraints doesn’t automatically enforce these constraints, just as annotating any fields or properties with bean constraints doesn’t enforce these either.
Instead method constraints must be validated by invoking the appropriate methods on javax.validation.executable.ExecutableValidator
. Typically this won’t happen by manually calling these methods but rather automatically upon invocation of the constrained methods or constructors, using approaches and techniques such as CDI/EJB interceptors, aspect-oriented programming or dynamic proxies.
The validation of method / constructor constraints comprises the following steps:
-
Intercept the method call to be validated
-
Validate the parameter values provided by the method caller using
ExecutableValidator.validateParameters()
orExecutableValidator.validateConstructorParameters()
. -
If this validation yields a non-empty set of constraint violations, throw a
ConstraintViolationException
wrapping the violations. Otherwise proceed with the actual method invocation. -
Validate the result returned by the invoked method using
ExecutableValidator.validateReturnValue()
orExecutableValidator.validateConstructorReturnValue()
. -
If this validation yields a non-empty set of constraint violations, throw a
ConstraintViolationException
wrapping the violations. Otherwise return the invocation result to the method caller.
By throwing a ConstraintViolationException
if either of the validation steps fails, it is ensured that the control flow
-
only arrives at the method’s body if the caller has satisfied the method’s preconditions and
-
only returns to the method caller if the method’s postconditions are guaranteed.
By default, integrators intercept and validate methods either hosting a constraint or being marked for cascaded validation (@Valid
) whether it be on the method itself or on any of its parameters. The Default
group is used for validation out of the box.
Integrators are encouraged to use Bean Validation’s metadata API to find whether or not a method or a constructor should be intercepted. This guarantees that XML descriptors as well as future mapping strategies are taken into account. Note that the metadata API does not take into account the fact that a method or constructor validation has been enabled or disabled by the techniques described in Method and constructor validation.
Here is an example of what such metadata usage would be:
//For methods
// is there any constrained method on this type
// assuming we don't validate on getter execution
public boolean interceptMethods(Class<?> type) {
return validator.getConstraintsForClass( type ).getConstrainedMethods(MethodType.NON_GETTER).size() > 0;
}
// is this method constrained
public boolean interceptMethod(Class<?> type, Method method) {
BeanDescriptor bean = validator.getConstraintsForClass( type );
MethodDescriptor methodDescriptor = bean.getConstraintsForMethod(
method.getName(), method.getParameterTypes() );
return methodDescriptor != null;
}
// should method parameters be validated
public boolean requiresParametersValidation(Class<?> type, Method method) {
BeanDescriptor bean = validator.getConstraintsForClass( type );
MethodDescriptor methodDescriptor = bean.getConstraintsForMethod(
method.getName(), method.getParameterTypes() );
if ( methodDescriptor != null ) {
return methodDescriptor.hasConstrainedParameters();
}
else {
return false;
}
}
// should method return value be validated?
public boolean requiresReturnValueValidation(Class<?> type, Method method) {
BeanDescriptor bean = validator.getConstraintsForClass( type );
MethodDescriptor methodDescriptor = bean.getConstraintsForMethod(
method.getName(), method.getParameterTypes() );
if ( methodDescriptor != null ) {
return methodDescriptor.hasConstrainedReturnValue();
}
else {
return false;
}
}
//For constructors
// is there any constrained constructor on this type
public <T> boolean interceptConstructors(Class<T> type) {
BeanDescriptor bean = validator.getConstraintsForClass( type );
return bean.getConstrainedConstructors().size() > 0;
}
// is this constructor constrained
public <T> boolean interceptConstructor(Class<T> type, Constructor<T> ctor) {
BeanDescriptor bean = validator.getConstraintsForClass( type );
ConstructorDescriptor constructorDescriptor = bean.getConstraintsForConstructor(
ctor.getParameterTypes() );
return constructorDescriptor != null;
}
// should constructor parameters be validated
public <T> boolean requiresParametersValidation(Class<T> type, Constructor<T> ctor) {
BeanDescriptor bean = validator.getConstraintsForClass( type );
ConstructorDescriptor constructorDescriptor = bean.getConstraintsForConstructor(
ctor.getParameterTypes() );
if ( constructorDescriptor != null ) {
return constructorDescriptor.hasConstrainedParameters();
}
else {
return false;
}
}
// should constructor return value be validated?
public <T> boolean requiresReturnValueValidation(Class<T> type, Constructor<T> ctor) {
BeanDescriptor bean = validator.getConstraintsForClass( type );
ConstructorDescriptor constructorDescriptor = bean.getConstraintsForConstructor(
ctor.getName(),
ctor.getParameterTypes()
);
if ( constructorDescriptor != null ) {
return constructorDescriptor.hasConstrainedReturnValue();
}
else {
return false;
}
}
Note
|
Calls to the metadata API is likely only going to be needed during the initialization phase of the interception framework. Results can then be cached. |
Note
|
Only methods or constructors intercepted by the underlying interception technology can be validated. |
The integration technology must put the validation interceptor as late as possible (if not last) in the interception stack. In particular, validation of parameters should be done after the security and transaction start logic. Likewise, return value validation should be done before the transaction stop logic. Putting the validation interceptor as late as possible in the stack ensures this.
Note
|
Why have the validation interceptor after other interceptors?
There are several reasons for delaying validation compared to other interceptors:
|
6.5. Bootstrapping
The bootstrapping API aims at providing a ValidatorFactory
object which is used to create Validator
instances. The bootstrap process is decoupled from the provider implementation initialization: a bootstrap implementation must be able to bootstrap any Bean Validation provider implementation. The bootstrap sequence has been designed to achieve several goals:
-
plug multiple implementations
-
choose a specific implementation
-
extensibility: an application using a specific provider implementation can use specific configurations
-
share and reuse of metadata across
Validator
s -
leave as much freedom as possible to implementations
-
provide integration mechanisms to Java EE (starting from version 6) and other containers
-
type safety
The main artifacts involved in the bootstrap process are:
-
Validation
: API entry point. Lets you optionally define the Bean Validation provider targeted as well as a provider resolution strategy.Validation
generatesConfiguration
objects and can bootstrap any provider implementation. -
ValidationProvider
: contract between the bootstrap procedure and a Bean Validation provider implementation. -
ValidationProviderResolver
: returns a list of all Bean Validation providers available in the execution context (generally the classpath). -
Configuration
: collects the configuration details that will be used to buildValidatorFactory
. A specific sub interface ofConfiguration
must be provided by Bean Validation providers. This sub interface typically hosts provider specific configurations. -
ValidatorFactory
: result of the bootstrap process. BuildValidator
instances from a given Bean Validation provider. -
META-INF/validation.xml
: a configuration file Bean Validation users can use to customize the configuration of the defaultValidatorFactory
.
Let’s first see the API in action through some examples before diving into the concrete definitions.
6.5.1. Examples
The most simple approach is to initialize the default Bean Validation provider or the one defined in the XML configuration file. The ValidatorFactory
is then ready to provide Validator
instances.
ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
//cache the factory somewhere
Validator validator = factory.getValidator();
//when the application shuts down, close ValidatorFactory
factory.close();
The ValidatorFactory
object is thread-safe. Building Validator
instances is typically a cheap operation. Building a ValidatorFactory
is typically more expensive. Make sure to check your Bean Validation implementation documentation for more accurate details.
The second example shows how a container can customize aspects like message interpolation, constraint validator instantiation and others.
//some customization from a container
ValidatorFactory factory = Validation
.byDefaultProvider().configure()
.messageInterpolator( new ContainerMessageInterpolator() )
.constraintValidatorFactory( new ContainerComponentConstraintValidatorFactory() )
.traversableResolver( new JPAAwareTraversableResolver() )
.parameterNameProvider( new AnnotationBasedParameterNameProvider() )
.clockProvider( new BatchJobClockProvider() )
.addValueExtractor( new TableValueExtractor() )
.addValueExtractor( new MultiMapValueExtractor() )
.buildValidatorFactory();
//cache the factory somewhere
Validator validator = factory.getValidator();
//when the application shuts down, close ValidatorFactory
factory.close();
The third example shows how to bootstrap Bean Validation in an environment not following the traditional Java class loader strategies (such as tools or alternative service containers like OSGi). They can provide some alternative provider resolution strategy to discover Bean Validation providers.
//osgi environment
ValidatorFactory factory = Validation
.byDefaultProvider()
.providerResolver( new OSGiServiceDiscoverer() )
.configure()
.buildValidatorFactory();
//cache the factory somewhere
Validator validator = factory.getValidator();
//when the bundle shuts down, close ValidatorFactory
factory.close();
The next example shows how a client can choose a specific Bean Validation provider and configure provider specific properties programmatically in a type-safe way.
ValidatorFactory factory = Validation
.byProvider( ACMEProvider.class ) //chose a specific provider
.configure()
.messageInterpolator( new ContainerMessageInterpolator() ) //default configuration option
.addConstraint(Address.class, customConstraintDescriptor) //ACME specific method
.buildValidatorFactory();
//same initialization decomposing calls
ACMEConfiguration acmeConfiguration = Validation
.byProvider( ACMEProvider.class )
.configure();
ValidatorFactory factory = acmeConfiguration
.messageInterpolator( new ContainerMessageInterpolator() ) //default configuration option
.addConstraint(Address.class, customConstraintDescriptor) //ACME specific method
.buildValidatorFactory();
/**
* ACME specific validator configuration and configuration options
*/
public interface ACMEConfiguration extends Configuration<ACMEConfiguration> {
/**
* Programmatically add constraints. Specific to the ACME provider.
*/
ACMEConfiguration addConstraint(Class<?> entity,
ACMEConstraintDescriptor constraintDescriptor);
}
/**
* ACME validation provider
* Note how ACMEConfiguration and ACMEProvider are linked together
* via the generic parameter.
*/
public class ACMEProvider implements ValidationProvider<ACMEConfiguration> {
[...]
}
The last example shows how a Validator
can use a specific MessageInterpolator
implementation.
ValidatorFactory factory = [...];
MessageInterpolator customInterpolator = new LocaleSpecificMessageInterpolator(
locale,
factory.getMessageInterpolator()
);
Validator localizedValidator =
factory.usingContext()
.messageInterpolator(customInterpolator)
.getValidator();
In the same way, a custom TraversableResolver
can be passed.
We will now explore the various interfaces, their constraints and usage. We will go from the ValidatorFactory
to the Validation
class walking up the bootstrap chain.
6.5.2. ValidatorFactory
ValidatorFactory
objects build and provide initialized instances of Validator
to Bean Validation clients. Each Validator
instance is configured for a given context (message interpolator, traversable resolver etc.). Clients should cache ValidatorFactory
objects and reuse them for optimal performances. The API is designed to allow implementors to share constraint metadata in ValidatorFactory
. ValidatorFactory
instances must be closed (by calling the close()
method) by its creator when no longer in use.
ValidatorFactory
implementations must be thread-safe. ValidatorFactory
implementations can cache Validator
instances if needed.
ValidatorFactory
interface/**
* Factory returning initialized {@code Validator} instances.
* <p>
* Implementations are thread-safe and instances are typically cached and reused.
*
* @author Emmanuel Bernard
* @author Gunnar Morling
* @author Hardy Ferentschik
* @author Guillaume Smet
*/
public interface ValidatorFactory extends AutoCloseable {
/**
* Returns an initialized {@link Validator} instance using the
* factory defaults for message interpolator, traversable resolver
* and constraint validator factory.
* <p>
* Validator instances can be pooled and shared by the implementation.
*
* @return an initialized {@code Validator} instance
*/
Validator getValidator();
/**
* Defines a new validator context and returns a {@code Validator}
* compliant this new context.
*
* @return a {@link ValidatorContext} instance
*/
ValidatorContext usingContext();
/**
* Returns the {@link MessageInterpolator} instance configured at
* initialization time for the {@code ValidatorFactory}.
* This is the instance used by {@link #getValidator()}.
*
* @return {@code MessageInterpolator} instance
*/
MessageInterpolator getMessageInterpolator();
/**
* Returns the {@link TraversableResolver} instance configured
* at initialization time for the {@code ValidatorFactory}.
* This is the instance used by {@link #getValidator()}.
*
* @return {@code TraversableResolver} instance
*/
TraversableResolver getTraversableResolver();
/**
* Returns the {@link ConstraintValidatorFactory} instance
* configured at initialization time for the
* {@code ValidatorFactory}.
* This is the instance used by {@link #getValidator()}.
*
* @return {@code ConstraintValidatorFactory} instance
*/
ConstraintValidatorFactory getConstraintValidatorFactory();
/**
* Returns the {@link ParameterNameProvider} instance configured at
* initialization time for the {@code ValidatorFactory}.
* This is the instance used by #getValidator().
*
* @return {@code ParameterNameProvider} instance
*
* @since 1.1
*/
ParameterNameProvider getParameterNameProvider();
/**
* Returns the {@link ClockProvider} instance configured at
* initialization time for the {@code ValidatorFactory}.
* This is the instance used by #getValidator().
*
* @return {@code ClockProvider} instance
*
* @since 2.0
*/
ClockProvider getClockProvider();
/**
* Returns an instance of the specified type allowing access to
* provider-specific APIs. If the Bean Validation provider
* implementation does not support the specified class, a
* {@code ValidationException} is thrown.
*
* @param type the class of the object to be returned
* @param <T> the type of the object to be returned
* @return an instance of the specified class
* @throws ValidationException if the provider does not
* support the call.
*/
public <T> T unwrap(Class<T> type);
/**
* Closes the {@code ValidatorFactory} instance.
*
* After the {@code ValidatorFactory} instance is closed, calling the following
* methods is not allowed:
* <ul>
* <li>methods of this {@code ValidatorFactory} instance</li>
* <li>methods of {@link Validator} instances created by this
* {@code ValidatorFactory}</li>
* </ul>
*
* @since 1.1
*/
@Override
public void close();
}
A ValidatorFactory
is provided by a Configuration
object.
unwrap()
is provided as a way to access objects of a given type specific to a Bean Validation provider typically as a complement to the ValidatorFactory
contract. Using this method makes your code non portable.
//if using the ACME provider
ACMEValidatorFactory acmeFactory = factory.unwrap(ACMEValidatorFactory.class);
acmeFactory.setSpecificConfiguration( [...] );
close()
closes the ValidatorFactory
instance which becomes unavailable and should be immediately discarded. This is also true of all the Validator
instances it has spawned. The behavior is undefined and non portable if these instances are used after the ValidatorFactory
has been closed.
getMessageInterpolator()
returns the MessageInterpolator
instance configured during the initialization of the ValidatorFactory
. It is particularly useful to build a Validator
specific MessageInterpolator
wrapping the one from the ValidatorFactory
.
getTraversableResolver()
returns the TraversableResolver
instance configured during the initialization of the ValidatorFactory
. It is particularly useful to build a Validator
specific TraversableResolver
wrapping the one from the ValidatorFactory
.
getConstraintValidatorFactory()
returns the ConstraintValidatorFactory
instance configured during the initialization of the ValidatorFactory
. It is particularly useful to build a Validator
specific ConstraintValidatorFactory
wrapping the one from the ValidatorFactory
.
getParameterNameProvider()
returns the ParameterNameProvider
instance configured during the initialization of the ValidatorFactory
. It is particularly useful to build a Validator
specific ParameterNameProvider
wrapping the one from the ValidatorFactory
.
getClockProvider()
returns the ClockProvider
instance configured during the initialization of the ValidatorFactory
. It is particularly useful to build a Validator
specific ClockProvider
wrapping the one from the ValidatorFactory
.
ValidatorContext
returned by usingContext()
can be used to customize the state in which the Validator
must be initialized. This is used to customize the MessageInterpolator
, the TraversableResolver
, the ParameterNameProvider
, the ClockProvider
or the ConstraintValidatorFactory
.
ValidatorContext
interface/**
* Represents the context that is used to create {@link Validator}
* instances.
*
* A client may use methods of the {@code ValidatorContext} returned by
* {@link ValidatorFactory#usingContext()} to customize
* the context used to create {@code Validator} instances
* (for instance establish different message interpolators or
* traversable resolvers).
*
* @author Emmanuel Bernard
* @author Gunnar Morling
* @author Guillaume Smet
*/
public interface ValidatorContext {
/**
* Defines the message interpolator implementation used by the
* {@link Validator}.
* <p>
* If not set or if {@code null} is passed as a parameter,
* the message interpolator of the {@link ValidatorFactory}
* is used.
*
* @param messageInterpolator the {@link MessageInterpolator} used by the
* {@code Validator}
*
* @return self following the chaining method pattern
*/
ValidatorContext messageInterpolator(MessageInterpolator messageInterpolator);
/**
* Defines the traversable resolver implementation used by the
* {@link Validator}.
* <p>
* If not set or if {@code null} is passed as a parameter,
* the traversable resolver of the {@link ValidatorFactory} is used.
*
* @param traversableResolver the {@code TraversableResolver} used by the
* {@code Validator}
* @return self following the chaining method pattern
*/
ValidatorContext traversableResolver(TraversableResolver traversableResolver);
/**
* Defines the constraint validator factory implementation used by the
* {@link Validator}.
* If not set or if {@code null} is passed as a parameter,
* the constraint validator factory of the {@link ValidatorFactory} is used.
*
* @param factory the {@link ConstraintValidatorFactory} used by the {@code Validator}
* @return self following the chaining method pattern
*/
ValidatorContext constraintValidatorFactory(ConstraintValidatorFactory factory);
/**
* Defines the parameter name provider implementation used by the
* {@link Validator}. If not set or if {@code null} is passed as a parameter,
* the parameter name provider of the {@link ValidatorFactory} is used.
*
* @param parameterNameProvider parameter name provider implementation.
* @return self following the chaining method pattern
*
* @since 1.1
*/
ValidatorContext parameterNameProvider(ParameterNameProvider parameterNameProvider);
/**
* Defines the {@link ClockProvider} implementation used by the {@link Validator}.
* If not set or if {@code null} is passed as a parameter,
* the clock provider of the {@link ValidatorFactory} is used.
*
* @param clockProvider {@code ClockProvider} implementation
* @return self following the chaining method pattern
*
* @since 2.0
*/
ValidatorContext clockProvider(ClockProvider clockProvider);
/**
* Adds a value extractor to be used by the {@link Validator}. Has
* priority over any extractor for the same type and type parameter
* detected through the service loader, given in the XML configuration or
* configured for the validator factory.
*
* @param extractor value extractor implementation
* @return self following the chaining method pattern
* @throws ValueExtractorDeclarationException if more than one extractor for
* the same type and type parameter is added
* @since 2.0
*/
ValidatorContext addValueExtractor(ValueExtractor<?> extractor);
/**
* Returns an initialized {@link Validator} instance respecting the defined state.
* {@code Validator} instances can be pooled and shared by the implementation.
*
* @return contextualized {@code Validator}
*/
Validator getValidator();
}
The MessageInterpolator
, the TraversableResolver
, the ConstraintValidatorFactory
, the ParameterNameProvider
or the ClockProvider
passed to the ValidatorContext
are used instead of the ValidatorFactory
's MessageInterpolator
, TraversableResolver
, ConstraintValidatorFactory
, ParameterNameProvider
or ClockProvider
instances.
A ValueExtractorDeclarationException
is raised if more than one extractor for the same type and type parameter is added via addValueExtractor()
.
ValidatorFactory factory = [...];
Validator validatorUsingDefaults = factory.getValidator();
Validator validatorUsingCustomTraversable = factory
.usingContext()
.traversableResolver( new JPATraversableResolver() )
.getValidator();
See Use MessageInterpolator to use a specific Locale value for an example using ValidatorFactory.getMessageInterpolator()
.
6.5.3. Configuration
The responsibility of the Configuration
is to collect configuration information, to determine the correct provider implementation and to delegate the ValidatorFactory
creation to the selected provider. More concretely Configuration
lets you define:
-
the message interpolator instance
-
the traversable resolver instance
-
the constraint validator factory instance
-
the parameter name provider instance
-
the clock provider instance
-
value extractor instances
-
XML constraint mappings
-
provider specific properties
-
whether or not
META-INF/validation.xml
is considered
Configuration
does provide a MessageInterpolator
implementation following the default Bean Validation MessageInterpolator
rules as defined in Default message interpolation. You can access it by calling getDefaultMessageInterpolator()
. Such an implementation is useful to let a custom MessageInterpolator
delegate to the standard MessageInterpolator
(see Custom message interpolation and an example making use of getDefaultMessageInterpolator()
in Contextual container possible MessageInterpolator
implementation).
Configuration
does provide a TraversableResolver
implementation following the default Bean Validation TraversableResolver
rules as defined in Traversable property. You can access it by calling getDefaultTraversableResolver()
. Such an implementation is useful to let a custom TraversableResolver
delegate to the standard TraversableResolver
.
Configuration
does provide a ConstraintValidatorFactory
implementation following the default Bean Validation ConstraintValidatorFactory
rules as defined in The ConstraintValidatorFactory. You can access it by calling getDefaultConstraintValidatorFactory()
. Such an implementation is useful to let a custom ConstraintValidatorFactory
delegate to the standard ConstraintValidatorFactory
.
Configuration
does provide a ParameterNameProvider
implementation following the default Bean Validation ParameterNameProvider
rules as defined in Naming parameters. You can access it by calling getDefaultParameterNameProvider()
. Such an implementation is useful to let a custom ParameterNameProvider
delegate to the standard ParameterNameProvider
.
Configuration
does provide a ClockProvider
implementation following the default Bean Validation ClockProvider
rules as defined in Implementation of temporal constraint validators. You can access it by calling getDefaultClockProvider()
.
Via getBootstrapConfiguration()
, Configuration
also exposes data stored in META-INF/validation.xml
(see XML configuration: META-INF/validation.xml). This is particularly useful for containers wishing to control the instance creation and lifecycle (more information at Bootstrapping considerations).
Note
|
|
Via addValueExtractor()
, additional value extractor implementations can be added to the configuration.
A value extractor for a given type and type parameter takes precedence over any extractor for the same type and type parameter
detected through the service loader or given in the XML configuration.
A ValueExtractorDeclarationException
is raised if more than one extractor for the same type and type parameter is added.
Using addMapping()
, additional constraint mapping XML descriptors can be added to the configuration (see XML configuration: META-INF/validation.xml). The given input streams should support the mark()
and reset()
methods defined by java.io.InputStream
. Streams not supporting the mark()
and reset()
methods will be wrapped with an InputStream
implementation supporting these methods by the Bean Validation provider in order to allow the streams to be read several times.
Clients call Configuration.buildValidatorFactory()
to retrieve the initialized ValidatorFactory
instance. It is legal to invoke buildValidatorFactory()
several times, e.g. in order to retrieve several ValidatorFactory
instances with a slightly different configuration (see Using Configuration to create several validator factories).
Configuration
and BootstrapConfiguration
interfaces/**
* Receives configuration information, selects the appropriate
* Bean Validation provider and builds the appropriate {@link ValidatorFactory}.
* <p>
* Usage:
* <pre>
* //provided by one of the Validation bootstrap methods
* Configuration<?> configuration =
* ValidatorFactory = configuration
* .messageInterpolator( new CustomMessageInterpolator() )
* .buildValidatorFactory();
* </pre>
* <p>
* By default, the configuration information is retrieved from
* {@code META-INF/validation.xml}.
* It is possible to override the configuration retrieved from the XML file
* by using one or more of the {@code Configuration} methods.
* <p>
* The {@link ValidationProviderResolver} is specified at configuration time
* (see {@link ValidationProvider}).
* If none is explicitly requested, the default {@code ValidationProviderResolver} is used.
* <p>
* The provider is selected in the following way:
* <ul>
* <li>if a specific provider is requested programmatically using
* {@link Validation#byProvider(Class)}, find the first provider implementing
* the provider class requested and use it</li>
* <li>if a specific provider is requested in {@code META-INF/validation.xml},
* find the first provider implementing the provider class requested and use it</li>
* <li>otherwise, use the first provider returned by the
* {@code ValidationProviderResolver}</li>
* </ul>
* <p>
* Implementations are not meant to be thread-safe.
*
* @param <T> the type of a provider-specific specialization of this contract
*
* @author Emmanuel Bernard
* @author Gunnar Morling
* @author Hardy Ferentschik
* @author Guillaume Smet
*/
public interface Configuration<T extends Configuration<T>> {
/**
* Ignores data from the {@code META-INF/validation.xml} file if this
* method is called.
* <p>
* This method is typically useful for containers that parse
* {@code META-INF/validation.xml} themselves and pass the information
* via the {@code Configuration} methods.
*
* @return {@code this} following the chaining method pattern.
*/
T ignoreXmlConfiguration();
/**
* Defines the message interpolator used. Has priority over the configuration
* based message interpolator.
* <p>
* If {@code null} is passed, the default message interpolator is used
* (defined in XML or the specification default).
*
* @param interpolator message interpolator implementation
* @return {@code this} following the chaining method pattern
*/
T messageInterpolator(MessageInterpolator interpolator);
/**
* Defines the traversable resolver used. Has priority over the configuration
* based traversable resolver.
* <p>
* If {@code null} is passed, the default traversable resolver is used
* (defined in XML or the specification default).
*
* @param resolver traversable resolver implementation
* @return {@code this} following the chaining method pattern
*/
T traversableResolver(TraversableResolver resolver);
/**
* Defines the constraint validator factory. Has priority over the configuration
* based constraint factory.
* <p>
* If {@code null} is passed, the default constraint validator factory is used
* (defined in XML or the specification default).
*
* @param constraintValidatorFactory constraint factory implementation
* @return {@code this} following the chaining method pattern
*/
T constraintValidatorFactory(ConstraintValidatorFactory constraintValidatorFactory);
/**
* Defines the parameter name provider. Has priority over the configuration
* based provider.
* <p>
* If {@code null} is passed, the default parameter name provider is used
* (defined in XML or the specification default).
*
* @param parameterNameProvider parameter name provider implementation
* @return {@code this} following the chaining method pattern.
*
* @since 1.1
*/
T parameterNameProvider(ParameterNameProvider parameterNameProvider);
/**
* Defines the clock provider. Has priority over the configuration
* based provider.
* <p>
* If {@code null} is passed, the default clock provider is used
* (defined in XML or the specification default).
*
* @param clockProvider clock provider implementation
* @return {@code this} following the chaining method pattern.
*
* @since 2.0
*/
T clockProvider(ClockProvider clockProvider);
/**
* Adds a value extractor. Has priority over any extractor for the same
* type and type parameter detected through the service loader or given in
* the XML configuration.
*
* @param extractor value extractor implementation
* @return {@code this} following the chaining method pattern.
* @throws ValueExtractorDeclarationException if more than one extractor for
* the same type and type parameter is added
* @since 2.0
*/
T addValueExtractor(ValueExtractor<?> extractor);
/**
* Add a stream describing constraint mapping in the Bean Validation XML
* format.
* <p>
* The stream should be closed by the client API after the
* {@link ValidatorFactory} has been built. The Bean Validation provider
* must not close the stream.
*
* @param stream
* XML mapping stream; the given stream should support the
* mark/reset contract (see {@link InputStream#markSupported()});
* if it doesn't, it will be wrapped into a stream supporting the
* mark/reset contract by the Bean Validation provider
*
* @return {@code this} following the chaining method pattern
* @throws IllegalArgumentException if {@code stream} is null
*/
T addMapping(InputStream stream);
/**
* Adds a provider specific property. This property is equivalent to
* XML configuration properties.
* If the underlying provider does not know how to handle the property,
* it must silently ignore it.
* <p>
* Note: Using this non type-safe method is generally not recommended.
* <p>
* It is more appropriate to use, if available, the type-safe equivalent provided
* by a specific provider via its {@link Configuration} subclass.
* <pre>
* ValidatorFactory factory = Validation.byProvider(ACMEProvider.class)
* .configure()
* .providerSpecificProperty(ACMEState.FAST)
* .buildValidatorFactory();
* </pre>
* This method is typically used by containers parsing {@code META-INF/validation.xml}
* themselves and injecting the state to the {@code Configuration} object.
* <p>
* If a property with a given name is defined both via this method and in the
* XML configuration, the value set programmatically has priority.
* <p>
* If {@code null} is passed as a value, the value defined in XML is used. If no value
* is defined in XML, the property is considered unset.
*
* @param name property name
* @param value property value
* @return {@code this} following the chaining method pattern
* @throws IllegalArgumentException if {@code name} is null
*/
T addProperty(String name, String value);
/**
* Returns an implementation of the {@link MessageInterpolator} interface
* following the default {@code MessageInterpolator} defined in the
* specification:
* <ul>
* <li>use the {@code ValidationMessages} resource bundle to load keys</li>
* <li>use {@code Locale.getDefault()}</li>
* </ul>
*
* @return default {@code MessageInterpolator} implementation compliant with the
* specification
*/
MessageInterpolator getDefaultMessageInterpolator();
/**
* Returns an implementation of the {@link TraversableResolver} interface
* following the default {@code TraversableResolver} defined in the
* specification:
* <ul>
* <li>if Java Persistence is available in the runtime environment,
* a property is considered reachable if Java Persistence considers
* the property as loaded</li>
* <li>if Java Persistence is not available in the runtime environment,
* all properties are considered reachable</li>
* <li>all properties are considered cascadable.</li>
* </ul>
*
* @return default {@code TraversableResolver} implementation compliant with the
* specification
*/
TraversableResolver getDefaultTraversableResolver();
/**
* Returns an implementation of the {@link ConstraintValidatorFactory} interface
* following the default {@code ConstraintValidatorFactory} defined in the
* specification:
* <ul>
* <li>uses the public no-arg constructor of the {@link ConstraintValidator}</li>
* </ul>
*
* @return default {@code ConstraintValidatorFactory} implementation compliant with the
* specification
*/
ConstraintValidatorFactory getDefaultConstraintValidatorFactory();
/**
* Returns an implementation of the {@link ParameterNameProvider}
* interface following the default {@code ParameterNameProvider}
* defined in the specification:
* <ul>
* <li>returns the actual parameter names as provided in the validated
* executableās definition, if the class file of the executable contains
* parameter name information</li>
* <li>
* otherwise returns names in the form {@code arg<PARAMETER_INDEX>},
* where {@code PARAMETER_INDEX} starts at 0 for the first parameter,
* e.g. {@code arg0}, {@code arg1} etc.</li>
* </ul>
*
* @return default {@code ParameterNameProvider} implementation compliant with
* the specification
*
* @since 1.1
*/
ParameterNameProvider getDefaultParameterNameProvider();
/**
* Returns an implementation of the {@link ClockProvider}
* interface following the default {@code ClockProvider}
* defined in the specification:
* <ul>
* <li>returns a clock representing the current system time and default time
* zone.</li>
* </ul>
*
* @return default {@code ClockProvider} implementation compliant with
* the specification
*
* @since 2.0
*/
ClockProvider getDefaultClockProvider();
/**
* Returns configuration information stored in the {@code META-INF/validation.xml} file.
* <p>
* <b>Note</b>:
* <br>
* Implementations are encouraged to lazily build this object to delay parsing.
*
* @return returns an instance of {@link BootstrapConfiguration}; this method never
* returns {@code null}; if there is no {@code META-INF/validation.xml} the
* different getters of the returned instance will return {@code null}
* respectively an empty set or map
*
* @since 1.1
*/
BootstrapConfiguration getBootstrapConfiguration();
/**
* Build a {@link ValidatorFactory} implementation.
*
* @return the {@code ValidatorFactory}
* @throws ValidationException if the {@code ValidatorFactory} cannot be built
*/
ValidatorFactory buildValidatorFactory();
}
/**
* Represents the user specified default configuration in
* {@code META-INF/validation.xml}.
* <p>
* Note that modifications to the returned objects do not have any effect.
* Instead use the methods provided on {@link Configuration} in order to
* apply modifications to the configuration.
*
* @author Emmanuel Bernard
* @author Gunnar Morling
* @author Hardy Ferentschik
* @author Guillaume Smet
* @since 1.1
*/
public interface BootstrapConfiguration {
/**
* Class name of the {@link ValidationProvider} implementation
* or {@code null} if none is specified.
*
* @return validation provider class name
*/
String getDefaultProviderClassName();
/**
* Class name of the {@link ConstraintValidatorFactory} implementation
* or {@code null} if none is specified.
*
* @return constraint validator factory class name
*/
String getConstraintValidatorFactoryClassName();
/**
* Class name of the {@link MessageInterpolator} implementation
* or {@code null} if none is specified.
*
* @return message interpolator class name or {@code null}
*/
String getMessageInterpolatorClassName();
/**
* Class name of the {@link TraversableResolver} implementation
* or {@code null} if none is specified.
*
* @return traversable resolver class name or {@code null}
*/
String getTraversableResolverClassName();
/**
* Class name of the {@link ParameterNameProvider} implementation
* or {@code null} if none is specified.
*
* @return parameter name provider class name or {@code null}
*/
String getParameterNameProviderClassName();
/**
* Class name of the {@link ClockProvider} implementation or
* {@code null} if none is specified.
*
* @return clock provider class name or {@code null}
*
* @since 2.0
*/
String getClockProviderClassName();
/**
* Returns the class names of {@link ValueExtractor}s.
*
* @return the value extractor class names or an empty set if none are specified
* @since 2.0
*/
Set<String> getValueExtractorClassNames();
/**
* Returns a set of resource paths pointing to XML constraint mapping files.
* The set is empty if none are specified.
*
* @return set of constraint mapping resource paths
*/
Set<String> getConstraintMappingResourcePaths();
/**
* Returns true if the validation execution is explicitly marked as enabled
* or if it is left undefined.
*
* @return whether validation execution is globally enabled
*/
boolean isExecutableValidationEnabled();
/**
* Returns the set of executable types that should be considered
* unless explicitly overridden via {@link ValidateOnExecution}
* <p>
* Returns a set containing {@link ExecutableType#CONSTRUCTORS} and
* {@link ExecutableType#NON_GETTER_METHODS} if unspecified in the configuration.
*
* @return set of validated executable types
*/
Set<ExecutableType> getDefaultValidatedExecutableTypes();
/**
* Returns properties as a map of string based key/value pairs.
* The map is empty if no property has been specified.
*
* @return the properties map
*/
Map<String, String> getProperties();
}
A Bean Validation provider must define a sub interface of Configuration
uniquely identifying the provider. This subclass is linked to its provider via the ValidationProvider
generic parameter. The Configuration
sub interface typically hosts provider specific configuration methods.
To facilitate the use of provider specific configuration methods, Configuration
uses generics: Configuration<T extends Configuration<T>>
; the generic return type T
is returned by chaining methods. The provider specific sub interface must resolve the generic T as itself as shown in Example of provider specific Configuration sub interface.
/**
* Unique identifier of the ACME provider
* also hosts some provider specific configuration methods
*/
public interface ACMEConfiguration
extends Configuration<ACMEConfiguration> {
/**
* Enables constraints implementation dynamic reloading when using ACME
* default to false
*/
ACMEConfiguration enableDynamicReloading(boolean);
}
When Configuration.buildValidatorFactory()
is called, the initialized ValidatorFactory
is returned. More specifically, the requested Bean Validation provider is determined and the result of validationProvider.buildValidatorFactory(ConfigurationState)
is returned. ConfigurationState
gives access to the configuration artifacts defined in META-INF/validation.xml
(unless XML configuration is ignored) and provided programmatically to Configuration
. Generally speaking, programmatically defined elements have priority over XML defined configuration elements (read the Configuration
JavaDoc and see XML configuration: META-INF/validation.xml for more information).
Note
|
A typical implementation of |
Streams represented in the XML configuration and opened by the Configuration
implementation must be closed by the Configuration
implementation after the ValidatorFactory
creation (or if an exception occurs). Streams provided programmatically are the responsibility of the application.
ConfigurationState
interfacepackage javax.validation.spi;
/**
* Contract between a {@link Configuration} and a
* {@link ValidationProvider} to create a {@link ValidatorFactory}.
* <p>
* The configuration artifacts defined in the XML configuration and provided to the
* {@code Configuration} are merged and passed along via
* {@code ConfigurationState}.
*
* @author Emmanuel Bernard
* @author Hardy Ferentschik
* @author Gunnar Morling
* @author Guillaume Smet
*/
public interface ConfigurationState {
/**
* Returns {@code true} if {@link Configuration#ignoreXmlConfiguration()} has been
* called.
* <p>
* In this case, the {@link ValidatorFactory} must ignore
* {@code META-INF/validation.xml}.
*
* @return {@code true} if {@code META-INF/validation.xml} should be ignored
*/
boolean isIgnoreXmlConfiguration();
/**
* Returns the message interpolator of this configuration.
* <p>
* Message interpolator is defined in the following decreasing priority:
* <ul>
* <li>set via the {@link Configuration} programmatic API</li>
* <li>defined in {@code META-INF/validation.xml} provided that
* {@code ignoreXmlConfiguration} is false. In this case the instance
* is created via its no-arg constructor.</li>
* <li>{@code null} if undefined.</li>
* </ul>
*
* @return message interpolator instance or {@code null} if not defined
*/
MessageInterpolator getMessageInterpolator();
/**
* Returns a set of configuration streams.
* <p>
* The streams are defined by:
* <ul>
* <li>mapping XML streams passed programmatically in {@link Configuration}</li>
* <li>mapping XML streams located in the resources defined in
* {@code META-INF/validation.xml} (constraint-mapping element)</li>
* </ul>
* <p>
* Streams represented in the XML configuration and opened by the
* {@code Configuration} implementation must be closed by the
* {@code Configuration} implementation after the {@link ValidatorFactory}
* creation (or if an exception occurs). All streams are guaranteed to
* adhere to the mark/reset contract (see {@link InputStream#markSupported()}
* by the Bean Validation provider.
*
* @return set of input stream
*/
Set<InputStream> getMappingStreams();
/**
* Returns a set of value extractors.
* <p>
* The extractors are retrieved from the following sources in decreasing
* order:
* <ul>
* <li>extractors passed programmatically to {@link Configuration}</li>
* <li>extractors defined in {@code META-INF/validation.xml} provided
* that {@code ignoredXmlConfiguration} is {@code false}</li>
* <li>extractors loaded through the Java service loader</li>
* </ul>
* An extractor for a given type and type parameter passed in
* programmatically takes precedence over any extractor for the same type
* and type parameter defined in {@code META-INF/validation.xml} or loaded
* through the service loader. Extractors defined in
* {@code META-INF/validation.xml} take precedence over any extractor for
* the same type and type parameter loaded through the service loader.
* <p>
* Extractors defined in {@code META-INF/validation.xml} or loaded through
* the service loader are instantiated using their no-arg constructor.
*
* @return set of value extractors; may be empty but never {@code null}
*
* @since 2.0
*/
Set<ValueExtractor<?>> getValueExtractors();
/**
* Returns the constraint validator factory of this configuration.
* <p>
* The {@link ConstraintValidatorFactory} implementation is defined in the following
* decreasing priority:
* <ul>
* <li>set via the {@link Configuration} programmatic API</li>
* <li>defined in {@code META-INF/validation.xml} provided that
* {@code ignoredXmlConfiguration} is {@code false}. In this case the instance
* is created via its no-arg constructor.</li>
* <li>{@code null} if undefined.</li>
* </ul>
*
* @return factory instance or {@code null} if not defined
*/
ConstraintValidatorFactory getConstraintValidatorFactory();
/**
* Returns the traversable resolver for this configuration.
* <p>
* {@link TraversableResolver} is defined in the following decreasing priority:
* <ul>
* <li>set via the {@link Configuration} programmatic API</li>
* <li>defined in {@code META-INF/validation.xml} provided that
* {@code ignoredXmlConfiguration} is {@code false}. In this case the
* instance is created via its no-arg constructor.</li>
* <li>{@code null} if undefined.</li>
* </ul>
*
* @return traversable resolver instance or {@code null} if not defined
*/
TraversableResolver getTraversableResolver();
/**
* Returns the parameter name provider for this configuration.
* <p>
* {@link ParameterNameProvider} is defined in the following decreasing priority:
* <ul>
* <li>set via the {@link Configuration} programmatic API</li>
* <li>defined in {@code META-INF/validation.xml} provided that
* {@code ignoreXmlConfiguration} is {@code false}. In this case the instance
* is created via its no-arg constructor.</li>
* <li>{@code null} if undefined.</li>
* </ul>
*
* @return parameter name provider instance or {@code null} if not defined
*
* @since 1.1
*/
ParameterNameProvider getParameterNameProvider();
/**
* Returns the clock provider for this configuration.
* <p>
* {@link ClockProvider} is defined in the following decreasing priority:
* <ul>
* <li>set via the {@link Configuration} programmatic API</li>
* <li>defined in {@code META-INF/validation.xml} provided that
* {@code ignoreXmlConfiguration} is {@code false}. In this case the instance
* is created via its no-arg constructor.</li>
* <li>{@code null} if undefined.</li>
* </ul>
*
* @return clock provider instance or {@code null} if not defined
*
* @since 2.0
*/
ClockProvider getClockProvider();
/**
* Returns a map of non type-safe custom properties.
* <p>
* Properties defined via:
* <ul>
* <li>{@link Configuration#addProperty(String, String)}</li>
* <li>{@code META-INF/validation.xml} provided that
* {@code ignoreXmlConfiguration} is {@code false}.</li>
* </ul>
* <p>
* If a property is defined both programmatically and in XML,
* the value defined programmatically has priority.
*
* @return {@code Map} whose key is the property key and the value
* the property value
*/
Map<String, String> getProperties();
}
The requested provider implementation is resolved according to the following rules in the following order:
-
Use the provider implementation requested if
Configuration
has been created fromValidation.byProvider(Class)
. -
Use the provider implementation described in the XML configuration (under
validation-config.default-provider
see XML configuration: META-INF/validation.xml) if defined: the value of this element is the fully qualified class name of theValidationProvider
implementation uniquely identifying the provider. -
Use the first provider implementation returned by
validationProviderResolver.getValidationProviders()
.
The ValidationProviderResolver
is specified when Configuration
instances are created (see ValidationProvider
). If no ValidationProviderResolver
instance has been specified, the default ValidationProviderResolver
is used.
Configuration
instances are provided to the Bean Validation client through the Validation
methods. Configuration
instances are created by ValidationProvider
.
If a problem occurs while building the ValidatorFactory
, a ValidationException
is raised. This can be due to various reasons including:
-
malformed XML configuration
-
malformed XML mapping
-
inability to find the provider (or a provider)
-
inability to instantiate extension classes provided in the XML configuration
-
inconsistent XML mapping (entity declared more than once, incorrect field etc.)
-
invalid constraint declaration or definition
Other exception causes may occur.
Here is an example of Configuration
use.
Configuration<?> configuration = [...];
ValidatorFactory factory = configuration
.messageInterpolator( new WBMessageInterpolator() )
.traversableResolver( new JPAAwareTraversableResolver() )
.buildValidatorFactory();
The following shows an example of setting up a Configuration
, retrieving a validator factory from it, subsequently altering the configuration and then retrieving another factory:
Configuration<?> configuration = [...];
ValidatorFactory factory1 = configuration
.messageInterpolator( new WBMessageInterpolator() )
.buildValidatorFactory();
ValidatorFactory factory2 = configuration
.traversableResolver( new JPAAwareTraversableResolver() )
.buildValidatorFactory();
Here, factory1
is set up using a custom message interpolator, while factory2
is set up using the same message interpolator and additionally using a custom traversable resolver.
6.5.4. ValidationProvider and ValidationProviderResolver
ValidationProvider
is the contract between the bootstrap process and a specific Bean Validation provider. ValidationProviderResolver
implements the discovery mechanism for Bean Validation provider implementations. Any Bean Validation client can implement such a discovery mechanism but it is typically implemented by containers having specific class loader structures and restrictions.
6.5.4.1. ValidationProviderResolver
ValidationProviderResolver
returns the list of Bean Validation providers available at runtime and more specifically a ValidationProvider
instance for each provider available in the context. This service can be customized by implementing ValidationProviderResolver
. Implementations must be thread-safe.
ValidationProviderResolver
interface/**
* Determines the list of Bean Validation providers available in the runtime environment
* <p>
* Bean Validation providers are identified by the presence of
* {@code META-INF/services/javax.validation.spi.ValidationProvider}
* files following the Service Provider pattern described
* <a href="http://docs.oracle.com/javase/8/docs/technotes/guides/jar/jar.html#Service_Provider">here</a>.
* <p>
* Each {@code META-INF/services/javax.validation.spi.ValidationProvider} file contains the
* list of {@link ValidationProvider} implementations each of them representing a provider.
* <p>
* Implementations must be thread-safe.
*
* @author Emmanuel Bernard
*/
public interface ValidationProviderResolver {
/**
* Returns a list of {@link ValidationProvider} available in the runtime environment.
*
* @return list of validation providers
*/
List<ValidationProvider<?>> getValidationProviders();
}
By default, providers are resolved using the Service Provider pattern described in http://docs.oracle.com/javase/6/docs/technotes/guides/jar/jar.html#Service%20Provider. Bean Validation providers must supply a service provider configuration file by creating a text file javax.validation.spi.ValidationProvider
and placing it in the META-INF/services
directory of one of its jar files. The content of the file contains the name of the provider implementation class of the javax.validation.spi.ValidationProvider
interface.
Bean Validation provider jars may be installed or made available in the same ways as other service providers, e.g. as extensions or added to the application classpath according to the guidelines in the JAR file specification.
The default ValidationProviderResolver
implementation will locate all the Bean Validation providers by their provider configuration files visible in the classpath. The default ValidationProviderResolver
implementation is recommended and custom ValidationProviderResolver
implementations should be rarely used. A typical use of a custom resolution is resolving providers in a class loader constrained container like OSGi or in a tool environment (IDE).
The default ValidationProviderResolver
can be accessed via BootStrapState.getDefaultValidationProviderResolver()
. This method is typically used by the Bean Validation provider Configuration
implementation.
6.5.4.2. ValidationProvider
ValidationProvider
represents the SPI (Service Provider Interface) defining the contract between the provider discovery and initialization mechanism, and the provider. A ValidationProvider
does:
-
Provide a generic
Configuration
implementation (i.e. not tied to a given provider). -
Provide a provider specific
Configuration
implementation. ThisConfiguration
will specifically buildValidatorFactory
instances of the provider it comes from. -
Build a
ValidatorFactory
object from the configuration provided byConfigurationState
.
ValidationProvider
interfacepackage javax.validation.spi;
/**
* Contract between the validation bootstrap mechanism and the provider engine.
* <p>
* Implementations must have a public no-arg constructor. The construction of a provider
* should be as "lightweight" as possible.
*
* @param <T> the provider specific Configuration subclass which typically host provider's
* additional configuration methods
*
* @author Emmanuel Bernard
* @author Hardy Ferentschik
*/
public interface ValidationProvider<T extends Configuration<T>> {
/**
* Returns a {@link Configuration} instance implementing {@code T},
* the {@code Configuration} sub-interface.
* The returned {@code Configuration} instance must use the current provider
* ({@code this}) to build the {@code ValidatorFactory} instance.
*
* @param state bootstrap state
* @return specific {@code Configuration} implementation
*/
T createSpecializedConfiguration(BootstrapState state);
/**
* Returns a {@link Configuration} instance. This instance is not bound to
* use the current provider. The choice of provider follows the algorithm described
* in {@code Configuration}
* <p>
* The {@link ValidationProviderResolver} used by {@code Configuration}
* is provided by {@code state}.
* If null, the default {@code ValidationProviderResolver} is used.
*
* @param state bootstrap state
* @return non specialized Configuration implementation
*/
Configuration<?> createGenericConfiguration(BootstrapState state);
/**
* Build a {@link ValidatorFactory} using the current provider implementation.
* <p>
* The {@code ValidatorFactory} is assembled and follows the configuration passed
* via {@link ConfigurationState}.
* <p>
* The returned {@code ValidatorFactory} is properly initialized and ready for use.
*
* @param configurationState the configuration descriptor
* @return the instantiated {@code ValidatorFactory}
* @throws ValidationException if the {@code ValidatorFactory} cannot be built
*/
ValidatorFactory buildValidatorFactory(ConfigurationState configurationState);
}
BootstrapState
interfacepackage javax.validation.spi;
/**
* Defines the state used to bootstrap the {@link Configuration}.
*
* @author Emmanuel Bernard
* @author Sebastian Thomschke
*/
public interface BootstrapState {
/**
* User defined {@code ValidationProviderResolver} strategy
* instance or {@code null} if undefined.
*
* @return ValidationProviderResolver instance or null
*/
ValidationProviderResolver getValidationProviderResolver();
/**
* Specification default {@code ValidationProviderResolver}
* strategy instance.
*
* @return default implementation of ValidationProviderResolver
*/
ValidationProviderResolver getDefaultValidationProviderResolver();
}
A client can request a specific Bean Validation provider by using <T extends Configuration<T>, U extends ValidationProvider<T>> Validation.byProvider(Class<U>)
or by defining the provider in the XML configuration file. The key uniquely identifying a Bean Validation provider is the ValidationProvider
implementation specific to this provider.
A ValidationProvider
implementation is linked (via its generic parameter) to a specific sub interface of Configuration
. The Bean Validation bootstrap API makes use of this link to return the specific Configuration
subinterface implementation in a type-safe way when a specific provider is requested. The sub interface does not have to add any new methods but is the natural holder for provider specific configuration methods.
/**
* Unique identifier of the ACME provider
* also hosts some provider specific configuration methods
*/
public interface ACMEConfiguration
extends Configuration<ACMEConfiguration> {
/**
* Enables constraints implementation dynamic reloading when using ACME
* default to false
*/
ACMEConfiguration enableDynamicReloading(boolean);
}
/**
* ACME validation provider
* Note how ACMEConfiguration and ACMEProvider are linked together
* via the generic parameter.
*/
public class ACMEProvider implements ValidationProvider<ACMEConfiguration> {
[...]
}
Note
|
|
The provider discovery mechanism uses the following algorithm:
-
Retrieve available providers using
ValidationProviderResolver.getValidationProviders()
. -
The first
ValidationProvider
matching the requested provider is returned. Providers are evaluated in the order they are returned byValidationProviderResolver
. A provider instance is considered matching if it is assignable to the requested provider class.
When the default Bean Validation provider is requested, the first ValidationProvider
returned by the ValidationProviderResolver
strategy is returned.
Every Bean Validation provider must provide a ValidationProvider
implementation containing a public no-arg constructor and add the corresponding META-INF/services/javax.validation.spi.ValidationProvider
file descriptor in one of its jars.
If a problem occurs while building the ValidatorFactory
, a ValidationException
is raised. This can be due to various reasons including:
-
malformed XML mapping
-
inability to find the provider (or a provider)
-
inability to instantiate extension classes provided in the XML configuration
-
inconsistent XML mapping (entity declared more than once, incorrect field etc.)
-
invalid constraint declaration or definition
6.5.5. Validation
The Validation
class is the entry point used to bootstrap Bean Validation providers. The first entry point, buildDefaultValidatorFactory()
, is considered to be the default ValidatorFactory
and is equivalent to the ValidatorFactory
returned by Validation.byDefaultProvider().configure().buildValidatorFactory()
.
/**
* This class is the entry point for Bean Validation.
* <p>
* There are three ways to bootstrap it:
* <ul>
* <li>The easiest approach is to build the default {@link ValidatorFactory}.
* <pre>
* ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
* </pre>
* In this case, the default validation provider resolver
* will be used to locate available providers.
* <p>
* The chosen provider is defined as followed:
* <ul>
* <li>if the XML configuration defines a provider, this provider is used</li>
* <li>if the XML configuration does not define a provider or if no XML
* configuration is present the first provider returned by the
* {@link ValidationProviderResolver} instance is used.</li>
* </ul>
* </li>
* <li>
* The second bootstrap approach allows to choose a custom
* {@code ValidationProviderResolver}. The chosen
* {@link ValidationProvider} is then determined in the same way
* as in the default bootstrapping case (see above).
* <pre>
* Configuration<?> configuration = Validation
* .byDefaultProvider()
* .providerResolver( new MyResolverStrategy() )
* .configure();
* ValidatorFactory factory = configuration.buildValidatorFactory();
* </pre>
* </li>
* <li>
* The third approach allows you to specify explicitly and in
* a type safe fashion the expected provider.
* <p>
* Optionally you can choose a custom {@code ValidationProviderResolver}.
* <pre>
* ACMEConfiguration configuration = Validation
* .byProvider(ACMEProvider.class)
* .providerResolver( new MyResolverStrategy() ) // optionally set the provider resolver
* .configure();
* ValidatorFactory factory = configuration.buildValidatorFactory();
* </pre>
* </li>
* </ul>
* <p>
* Note:
* <ul>
* <li>
* The {@code ValidatorFactory} object built by the bootstrap process should be cached
* and shared amongst {@code Validator} consumers.
* </li>
* <li>This class is thread-safe.</li>
* </ul>
*
* @author Emmanuel Bernard
* @author Hardy Ferentschik
*/
public class Validation {
/**
* Builds and returns a {@link ValidatorFactory} instance based on the
* default Bean Validation provider and following the XML configuration.
* <p>
* The provider list is resolved using the default validation provider resolver
* logic.
* <p>
* The code is semantically equivalent to
* {@code Validation.byDefaultProvider().configure().buildValidatorFactory()}.
*
* @return {@code ValidatorFactory} instance
*
* @throws NoProviderFoundException if no Bean Validation provider was found
* @throws ValidationException if a Bean Validation provider was found but the
* {@code ValidatorFactory} cannot be built
*/
public static ValidatorFactory buildDefaultValidatorFactory() {
[...]
}
/**
* Builds a {@link Configuration}. The provider list is resolved
* using the strategy provided to the bootstrap state.
* <pre>
* Configuration<?> configuration = Validation
* .byDefaultProvider()
* .providerResolver( new MyResolverStrategy() )
* .configure();
* ValidatorFactory factory = configuration.buildValidatorFactory();
* </pre>
* The provider can be specified in the XML configuration. If the XML
* configuration does not exist or if no provider is specified,
* the first available provider will be returned.
*
* @return instance building a generic {@code Configuration}
* compliant with the bootstrap state provided
*/
public static GenericBootstrap byDefaultProvider() {
[...]
}
/**
* Builds a {@link Configuration} for a particular provider implementation.
* <p>
* Optionally overrides the provider resolution strategy used to determine the provider.
* <p>
* Used by applications targeting a specific provider programmatically.
* <pre>
* ACMEConfiguration configuration =
* Validation.byProvider(ACMEProvider.class)
* .providerResolver( new MyResolverStrategy() )
* .configure();
* </pre>,
* where {@code ACMEConfiguration} is the
* {@code Configuration} sub interface uniquely identifying the
* ACME Bean Validation provider. and {@code ACMEProvider} is the
* {@link ValidationProvider} implementation of the ACME provider.
*
* @param providerType the {@code ValidationProvider} implementation type
* @param <T> the type of the {@code Configuration} corresponding to this
* {@code ValidationProvider}
* @param <U> the type of the {@code ValidationProvider} implementation
*
* @return instance building a provider specific {@code Configuration}
* sub interface implementation
*/
public static <T extends Configuration<T>, U extends ValidationProvider<T>>
ProviderSpecificBootstrap<T> byProvider(Class<U> providerType) {
[...]
}
[...]
}
The second entry point lets the client provide a custom ValidationProviderResolver
instance. This instance is passed to GenericBootstrap
. GenericBootstrap
builds a generic Configuration
using the first ValidationProvider
returned by ValidationProviderResolution
and calling ValidationProvider.createGenericConfiguration(BootstrapState state)
. BootstrapState
holds the ValidationProviderResolution
instance passed to GenericBootstrap
and will be used by the Configuration
instance when resolving the provider to use. Note that ValidationProvider.createGenericConfiguration
returns a Configuration
object not bound to any particular provider.
GenericBootstrap
interfacepackage javax.validation.bootstrap;
/**
* Defines the state used to bootstrap Bean Validation and
* creates a provider agnostic {@link Configuration}.
*
* @author Emmanuel Bernard
*/
public interface GenericBootstrap {
/**
* Defines the provider resolution strategy.
* This resolver returns the list of providers evaluated
* to build the {@link Configuration}.
* <p>
* If no resolver is defined, the default {@link ValidationProviderResolver}
* implementation is used.
*
* @param resolver the {@code ValidationProviderResolver} to use for bootstrapping
* @return {@code this} following the chaining method pattern
*/
GenericBootstrap providerResolver(ValidationProviderResolver resolver);
/**
* Returns a generic {@link Configuration} implementation.
* At this stage the provider used to build the {@link ValidatorFactory}
* is not defined.
* <p>
* The {@code Configuration} implementation is provided by the first provider
* returned by the {@link ValidationProviderResolver} strategy.
*
* @return a {@code Configuration} implementation compliant with the bootstrap state
* @throws NoProviderFoundException if no Bean Validation provider was found
* @throws ValidationException if a Bean Validation provider was found but the
* {@code Configuration} object cannot be built; this is generally due to an
* issue with the {@code ValidationProviderResolver}
*/
Configuration<?> configure();
}
The last entry point lets the client define the specific Bean Validation provider requested as well as a custom ValidationProviderResolver
implementation if needed. The entry point method, Validation.byProvider(Class<U> providerType)
, takes the provider specific ValidationProvider
implementation type and returns a ProviderSpecificBootstrap
object that guarantees to return an instance of the specific Configuration
sub interface. Thanks to the use of generics, the client API does not have to cast to the Configuration
sub interface.
A ProviderSpecificBootstrap
object can optionally receive a ValidationProviderResolver
instance.
ProviderSpecificBootstrap
interfacepackage javax.validation.bootstrap;
/**
* Defines the state used to bootstrap Bean Validation and
* creates a provider specific {@link Configuration}
* of type {@code T}.
* <p>
* The specific {@code Configuration} is linked to the provider via the generic
* parameter of the {@link ValidationProvider} implementation.
* <p>
* The requested provider is the first provider instance assignable to
* the requested provider type (known when {@link ProviderSpecificBootstrap} is built).
* The list of providers evaluated is returned by {@link ValidationProviderResolver}.
* If no {@code ValidationProviderResolver} is defined, the
* default {@code ValidationProviderResolver} strategy is used.
*
* @param <T> the provider specific {@link Configuration} type
*
* @author Emmanuel Bernard
*/
public interface ProviderSpecificBootstrap<T extends Configuration<T>> {
/**
* Optionally defines the provider resolver implementation used.
* If not defined, use the default {@link ValidationProviderResolver}
*
* @param resolver {@code ValidationProviderResolver} implementation used
*
* @return {@code this} following the chaining method pattern
*/
public ProviderSpecificBootstrap<T> providerResolver(
ValidationProviderResolver resolver);
/**
* Determines the provider implementation suitable for {@code T} and delegates
* the creation of this specific {@link Configuration} subclass to the provider.
*
* @return {@code Configuration} sub interface implementation
*
* @throws ValidationException if the {@code Configuration} object cannot be built;
* this is generally due to an issue with the {@code ValidationProviderResolver}
*/
public T configure();
}
ProviderSpecificBootstrap.configure()
must return the result of ValidationProvider.createSpecializedConfiguration(BootstrapState state)
. The state parameter holds the ValidationProviderResolver
passed to ProviderSpecificBootstrap
. The validation provider instance used is the one assignable to the type passed as a parameter in Validation.byProvider(Class)
. The validation provider is selected according to the algorithm described in ValidationProvider.
The Validation
implementation must not contain any non private attribute or method aside from the three public static bootstrap methods:
-
public static ValidatorFactory buildDefaultValidatorFactory()
-
public static GenericBootstrap byDefaultProvider()
-
public static <T extends Configuration<T>, U extends ValidationProvider<T>> ProviderSpecificBootstrap<T> byProvider(Class<U> providerType)
The bootstrap API is designed to allow complete portability among Bean Validation provider implementations. The bootstrap implementation must ensure it can bootstrap third party providers.
When bootstrapping a Bean Validation provider, if the ValidationProviderResolver
either fails or if the expected provider is not found, a ValidationException
is raised.
6.5.6. XML configuration: META-INF/validation.xml
Unless explicitly ignored by calling Configuration.ignoreXMLConfiguration()
, a Configuration
takes into account the configuration available in META-INF/validation.xml
. This configuration file is optional but can be used by applications to refine some of the Bean Validation behavior. If more than one META-INF/validation.xml
file is found in the classpath, a ValidationException
is raised.
Unless stated otherwise, XML based configuration settings are overridden by values explicitly set via the Configuration
API. For example, the MessageInterpolator
defined via Configuration.messageInterpolator(MessageInterpolator)
has priority over the message-interpolator
definition.
default-provider
: represents the class name of the provider specific ValidationProvider
implementation class. If defined, the specific provider is used (unless a specific provider has been chosen via the programmatic approach).
message-interpolator
: represents the fully qualified class name of the MessageInterpolator
implementation. When defined in XML, the implementation must have a public no-arg constructor.
traversable-resolver
: represents the fully qualified class name of the TraversableResolver
implementation. When defined in XML, the implementation must have a public no-arg constructor.
constraint-validator-factory
: represents the fully qualified class name of the ConstraintValidatorFactory
implementation. When defined in XML, the implementation must have a public no-arg constructor.
parameter-name-provider
: represents the fully qualified class name of the ParameterNameProvider
implementation. When defined in XML, the implementation must have a public no-arg constructor.
clock-provider
: represents the fully qualified class name of the ClockProvider
implementation. When defined in XML, the implementation must have a public no-arg constructor.
value-extractor
: represents the fully qualified class name of a ValueExtractor
implementation.
value-extractor
can be given several times for declaring multiple extractors.
When defined in XML, the implementation must have a public no-arg constructor.
An extractor for a given type and type parameter configured via XML takes precedence
over any extractor for the same type and type parameter detected through the service loader or provided by the Bean Validation implementation itself.
If more than one value extractor for the same type and type parameter is configured via XML, a ValueExtractorDeclarationException
is raised.
executable-validation
: allows to disable executable validation entirely via its attribute enabled="false"
and optionally contains default-validated-executable-types
. enabled
defaults to true
.
default-validated-executable-types
: declared under executable-validation
, contains the list of executable-type
that are considered by default by the integration technology validating executables upon execution.
constraint-mapping
: represents the resource path of an XML mapping file. More than one constraint-mapping
element can be present. Mappings provided via Configuration.addMapping(InputStream)
are added to the list of mappings described via constraint-mapping
.
property
: represents a key/value pair property providing room to provider specific configurations. Vendors should use vendor namespaces for properties (e.g., com.acme.validation.logging
). Entries that make use of the namespace javax.validation
and its subnamespaces must not be used for vendor-specific information. The namespace javax.validation
is reserved for use by this specification. Properties defined via Configuration.addProperty(String, String)
are added to the properties defined via property
. If a property with the same name are defined in both XML and via the programmatic API, the value provided via programmatic API has priority.
All these top level elements are optional.
If a public no-arg constructor is missing on any of the classes referenced by the relevant XML elements, a ValidationException
is raised during the Configuration.buildValidatorFactory()
call.
<?xml version="1.0" encoding="UTF-8"?>
<validation-config
xmlns="http://xmlns.jcp.org/xml/ns/validation/configuration"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/validation/configuration
http://xmlns.jcp.org/xml/ns/validation/configuration/validation-configuration-2.0.xsd"
version="2.0">
<default-provider>com.acme.ACMEProvider</default-provider>
<message-interpolator>com.acme.ACMEAwareMessageInterpolator</message-interpolator>
<executable-validation>
<default-validated-executable-types>
<executable-type>NONE</executable-type>
</default-validated-executable-types>
</executable-validation>
<constraint-mapping>META-INF/validation/order-constraints.xml</constraint-mapping>
<constraint-mapping>META-INF/validation/catalog-constraints.xml</constraint-mapping>
<constraint-mapping>META-INF/validation/customer-constraints.xml</constraint-mapping>
<property name="com.acme.validation.logging">WARN</property>
<property name="com.acme.validation.safetyChecking">failOnError</property>
</validation-config>
The XML schema is described in Configuration schema.
6.5.7. Bootstrapping considerations
The Bean Validation bootstrap API can be used directly by any application or made available through a container or other framework. In all cases, the following rules apply:
-
ValidatorFactory
is a thread-safe object that should be built once per deployment unit. -
ValidatorFactory
should be closed when it is no longer needed (e.g. when the unit is undeployed or the server stopped). -
Validator
is a thread-safe and lightweight object which can be cached by theValidatorFactory
instance.
7. Constraint metadata request APIs
The Bean Validation specification provides a way to query the constraint repository. This API is expected to be used for tooling support as well as integration with other frameworks, libraries and JSRs. The Bean Validation specification aims to provide both a validation engine and a metadata repository for object constraints. Frameworks (EE or SE) in need for constraint definition, validation and metadata will be able to rely on the Bean Validation specification for these services avoiding any unnecessary duplication work from an application and infrastructure point of view.
7.1. Validator
The main API to access all metadata related to a given object is Validator
(see Bootstrapping for more information on how to retrieve a Validator
instance).
A Validator
instance hosts the method to access to the metadata repository for a given class. It is recommended to leave the caching of Validator
instances to the ValidatorFactory
. Validator
implementations are thread-safe.
/**
* Validates bean instances. Implementations of this interface must be thread-safe.
*
* @author Emmanuel Bernard
* @author Hardy Ferentschik
* @author Gunnar Morling
*/
public interface Validator {
[...] //See 5.1
/**
* Returns the descriptor object describing bean constraints.
* <p>
* The returned object (and associated objects including
* {@link ConstraintDescriptor}s) are immutable.
*
* @param clazz class or interface type evaluated
* @return the bean descriptor for the specified class
* @throws IllegalArgumentException if clazz is {@code null}
* @throws ValidationException if a non recoverable error happens
* during the metadata discovery or if some
* constraints are invalid.
*/
BeanDescriptor getConstraintsForClass(Class<?> clazz);
}
getConstraintsForClass()
returns a BeanDescriptor
object describing the bean level constraints (see Object validation) and providing access to the property level constraints metadata. An IllegalArgumentException
is raised if the clazz
parameter is null.
If a constraint definition or declaration hosted by the requested class (or any of its superclasses and interfaces according to the constraint propagation rules) is invalid, a ValidationException
is raised. This can be a subclass of ValidationException
like ConstraintDefinitionException
, ConstraintDeclarationException
or UnexpectedTypeException
.
All descriptor types accessible via getConstraintsForClass()
and introduced in the following sections are located in the package javax.validation.metadata
.
7.2. ElementDescriptor
ElementDescriptor
is the root interface describing elements hosting constraints. It is used to describe the list of constraints for a given element (whether it be a class, property, method etc.).
ElementDescriptor
interface and Scope
enumpackage javax.validation.metadata;
/**
* Describes a validated element (class, property, method etc.).
*
* @author Emmanuel Bernard
* @author Hardy Ferentschik
* @author Gunnar Morling
*/
public interface ElementDescriptor {
/**
* @return returns {@code true} if at least one constraint declaration is present
* for this element in the class hierarchy, {@code false} otherwise
*/
boolean hasConstraints();
/**
* @return the statically defined returned type
*/
Class<?> getElementClass();
/**
* Returns all constraint descriptors for this element in the class hierarchy
* or an empty {@code Set} if none are present.
*
* @return {@code Set} of constraint descriptors for this element
*/
Set<ConstraintDescriptor<?>> getConstraintDescriptors();
/**
* Finds constraints and potentially restricts them to certain criteria.
*
* @return {@code ConstraintFinder} object
*/
ConstraintFinder findConstraints();
/**
* Declares restrictions on retrieved constraints.
* Restrictions are cumulative.
* <p>
* A {@code ConstraintFinder} is not thread-safe. The set of matching
* {@link ConstraintDescriptor} is.
*/
interface ConstraintFinder {
/**
* Restricts to the constraints matching a given set of groups for this element.
* <p>
* This method respects group conversion, group sequences
* and group inheritance (including class-level {@link Default} group
* overriding) but does not return {@link ConstraintDescriptor}s
* in any particular order.
* Specifically, ordering of the group sequence is not respected.
*
* @param groups groups targeted
* @return {@code this} following the chaining method pattern
*/
ConstraintFinder unorderedAndMatchingGroups(Class<?>... groups);
/**
* Restricts to the constraints matching the provided scope for this element.
*
* Defaults to {@link Scope#HIERARCHY}
*
* @param scope expected scope
* @return {@code this} following the chaining method pattern
*/
ConstraintFinder lookingAt(Scope scope);
/**
* Restricts to the constraints hosted on the listed {@code types}
* for a given element.
* <p>
* Defaults to all possible types of the element.
* <p>
* Typically used to restrict to fields ({@code FIELD})
* or getters ({@code METHOD}).
*
* @param types targeted types
*
* @return {@code this} following the chaining method pattern
*/
ConstraintFinder declaredOn(ElementType... types);
/**
* Retrieves the constraint descriptors following the defined
* restrictions and hosted on the element described by
* {@link ElementDescriptor}.
*
* @return matching constraint descriptors
*/
Set<ConstraintDescriptor<?>> getConstraintDescriptors();
/**
* Returns {@code true} if at least one constraint declaration
* matching the restrictions is present on the element,
* {@code false} otherwise.
*
* @return {@code true} if there is at least one constraint
*/
boolean hasConstraints();
}
}
Scope
enumpackage javax.validation.metadata;
/**
* Scope looked at when discovering constraints.
*
* @author Emmanuel Bernard
*/
public enum Scope {
/**
* Look for constraints declared on the current class element
* and ignore inheritance and elements with the same name in
* the class hierarchy.
*/
LOCAL_ELEMENT,
/**
* Look for constraints declared on all elements of the class hierarchy
* with the same name.
*/
HIERARCHY
}
getElementClass()
returns
-
the object type when invoked on
BeanDescriptor
, -
the type of a property or parameter when invoked on
PropertyDescriptor
orParameterDescriptor
respectively, -
Object[].class
when invoked onCrossParameterDescriptor
, -
the return type when invoked on
ConstructorDescriptor
,MethodDescriptor
orReturnValueDescriptor
, -
the container element type when invoked on
ContainerElementTypeDescriptor
(e.g. when invoked on a descriptor representing the container element type ofList<String>
,String.class
will be returned).
getConstraintDescriptors()
returns all the ConstraintDescriptor
s (see ConstraintDescriptor) hosted on the given element in the class hierarchy, each ConstraintDescriptor
describing one of the constraints declared on the given element.
hasConstraints()
returns true
if the given element in the class hierarchy holds at least one constraint declaration.
If you need to query the metadata API in a more fine grained way for example by restricting the constraints to the ones described on fields or on getters or by restricting to a given set of groups, you can use the ConstraintFinder
fluent API by calling findConstraints()
.
unorderedAndMatchingGroups()
restricts the results to the ConstraintDescriptor
s (see ConstraintDescriptor) matching the given groups. Order is not respected but group inheritance and inheritance via sequence (including the Default
group overriding at the class level) are honored.
declaredOn()
lets you restrict the list of element types constraints are hosted on. This is particularly useful to retrieve property constraints only hosted on fields (ElementType.FIELD
) or only hosted on getters (ElementType.METHOD
).
lookingAt()
lets you restrict which constraints are considered. Either constraints belonging to the element but hosted on the class represented by the given descriptor (Scope.LOCAL_ELEMENT
), or constraints belonging to the element but hosted anywhere in the class hierarchy (Scope.HIERARCHY
).
Here is an example restricting the list of constraints on getters, matching the default group and declared physically on the name
getter of Customer
(and not any of the getters on the super classes).
public class User {
@Size(max=50)
String getName() {
[...]
}
[...]
}
public class Customer extends User {
@NotNull
String getName() {
[...]
}
}
PropertyDescriptor pd =
validator.getConstraintsForClass(Customer.class).getConstraintsForProperty("name");
Set<ConstraintDescriptor<?>> constraints =
pd.findConstraints()
.declaredOn(ElementType.METHOD)
.unorderedAndMatchingGroups(Default.class)
.lookingAt(Scope.LOCAL_ELEMENT)
.getConstraintDescriptors();
assert 1 == constraints.size();
constraints = pd.getConstraintDescriptors();
//equivalent to pd.findConstraints().getConstraintDescriptors();
assert 2 == constraints.size();
The following example shows how the fluent API is used to retrieve parameter, cross-parameter and return value constraints, taking into account locally declared constraints as well as constraints declared in the inheritance hierarchy.
public class User {
public User(@Size(max=50) String name) {
[...]
}
@PasswordParametersMatch
@NotNull
public String resetPassword(
@NotNull @Size(min=8) String password,
@NotNull @Size(min=8) String confirmation) {
[...]
}
}
public class Customer extends User {
public Customer(@NotNull String name) {
[...]
}
@Size(min=8)
public String resetPassword(String password, String confirmation) {
[...]
}
}
MethodDescriptor methodDescriptor = validator
.getConstraintsForClass( Customer.class )
.getConstraintsForMethod( "resetPassword", String.class, String.class );
//one cross-parameter constraint
assert 1 == methodDescriptor.getCrossParameterDescriptor().getConstraintDescriptors().size();
//one local return value constraint
assert 1 == methodDescriptor.getReturnValueDescriptor()
.findConstraints()
.lookingAt( Scope.LOCAL_ELEMENT )
.getConstraintDescriptors()
.size();
//two return value constraints in the complete hierarchy
assert 2 == methodDescriptor.getReturnValueDescriptor()
.findConstraints()
.lookingAt( Scope.HIERARCHY )
.getConstraintDescriptors()
.size();
//two parameter constraints, defined on overridden method
assert 2 == methodDescriptor.getParameterDescriptors()
.get( 0 )
.getConstraintDescriptors()
.size();
ConstructorDescriptor constructorDescriptor = validator
.getConstraintsForClass( Customer.class )
.getConstraintsForConstructor( String.class );
//one parameter constraint; constraints from super constructor don't apply
assert 1 == constructorDescriptor.getParameterDescriptors()
.get( 0 )
.findConstraints()
.lookingAt( Scope.HIERARCHY )
.getConstraintDescriptors()
.size();
7.3. BeanDescriptor
The BeanDescriptor
interface describes a constrained Java Bean. This interface is returned by Validator.getConstraintsForClass(Class<?>)
.
BeanDescriptor
interfacepackage javax.validation.metadata;
/**
* Describes a constrained Java Bean and the constraints associated to it. All
* objects returned by the methods of this descriptor (and associated objects
* including {@link ConstraintDescriptor}s) are immutable.
*
* @author Emmanuel Bernard
* @author Gunnar Morling
*/
public interface BeanDescriptor extends ElementDescriptor {
/**
* Returns {@code true} if the bean involves validation:
* <ul>
* <li>a constraint is hosted on the bean itself</li>
* <li>a constraint is hosted on one of the bean properties</li>
* <li>or a bean property is marked for cascaded validation ({@link Valid})</li>
* </ul>
* <p>
* Constrained methods and constructors are ignored.
*
* @return {@code true} if the bean involves validation, {@code false} otherwise
*/
boolean isBeanConstrained();
/**
* Returns the property descriptor for a given property.
* <p>
* Returns {@code null} if the property does not exist or has no
* constraint nor is marked as cascaded (see {@link #getConstrainedProperties()})
* Properties of super types are considered.
*
* @param propertyName property evaluated
* @return the property descriptor for a given property
* @throws IllegalArgumentException if {@code propertyName} is {@code null}
*/
PropertyDescriptor getConstraintsForProperty(String propertyName);
/**
* Returns a set of property descriptors having at least one constraint defined
* or marked as cascaded ({@link Valid}).
* <p>
* If no property matches, an empty set is returned.
* Properties of super types are considered.
*
* @return the set of {@link PropertyDescriptor}s for the constraint properties; if
* there are no constraint properties, the empty set is returned
*/
Set<PropertyDescriptor> getConstrainedProperties();
/**
* Returns a method descriptor for the given method.
* <p>
* Returns {@code null} if no method with the given name and parameter types
* exists or the specified method neither has parameter or return value constraints nor a
* parameter or return value marked for cascaded validation.
* Methods of super types are considered.
*
* @param methodName the name of the method
* @param parameterTypes the parameter types of the method
* @return a method descriptor for the given method
* @throws IllegalArgumentException if {@code methodName} is {@code null}
*
* @since 1.1
*/
MethodDescriptor getConstraintsForMethod(String methodName, Class<?>... parameterTypes);
/**
* Returns a set with descriptors for the constrained methods of the bean
* represented by this descriptor.
* <p>
* Constrained methods have at least one parameter or return value constraint
* or at least one parameter or return value marked for cascaded validation.
* Methods of super types are considered.
* <p>
* Only methods matching the given method type(s) are considered.
*
* @param methodType method type to consider
* @param methodTypes remaining optional method types to consider
* @return a set with descriptors for the constrained methods of this bean;
* will be empty if this bean has no constrained methods of the considered
* method type(s) but never {@code null}
*
* @since 1.1
*/
Set<MethodDescriptor> getConstrainedMethods(MethodType methodType,
MethodType... methodTypes);
/**
* Returns a constructor descriptor for the given constructor.
* <p>
* Returns {@code null} if no constructor with the given parameter types
* exists or the specified constructor neither has parameter or return value
* constraints nor a parameter or return value marked for cascaded
* validation.
*
* @param parameterTypes the parameter types of the constructor
* @return a constructor descriptor for the given constructor
*
* @since 1.1
*/
ConstructorDescriptor getConstraintsForConstructor(Class<?>... parameterTypes);
/**
* Returns a set with descriptors for the constrained constructors of the
* bean represented by this descriptor.
* <p>
* Constrained constructors have at least one parameter or return value constraint
* or at least one parameter or return value marked for cascaded validation.
*
* @return a set with descriptors for the constrained constructor of this
* bean; will be empty if this bean has no constrained constructor
* but never {@code null}
*
* @since 1.1
*/
Set<ConstructorDescriptor> getConstrainedConstructors();
}
MethodType
enumpackage javax.validation.metadata;
/**
* Represents the type of a method: getter or non getter.
*
* @author Emmanuel Bernard
* @since 1.1
*/
public enum MethodType {
/**
* A method following the getter pattern. A getter according to the
* JavaBeans specification is a method whose:
* <ul>
* <li>name starts with get, has a return type but no parameter</li>
* <li>name starts with is, has a return type and is returning {@code boolean}.</li>
* </ul>
*/
GETTER,
/**
* A method that does not follow the getter pattern. A getter according to the
* JavaBeans specification is a method whose:
* <ul>
* <li>name starts with get, has a return type but no parameter</li>
* <li>name starts with is, has a return type and is returning {@code boolean}.</li>
* </ul>
*/
NON_GETTER
}
isBeanConstrained()
returns true
if the given class (and superclasses and interfaces) has at least one class-level or property-level constraint or validation cascade. If the method returns false, the Bean Validation engine can safely ignore the bean as it will not be impacted by validation.
getConstraintsForProperty()
returns a PropertyDescriptor
object describing the property level constraints (See Field and property validation). The property is uniquely identified by its name as per the JavaBeans convention: field level and getter level constraints of the given name are all returned. An IllegalArgumentException
is raised if the propertyName
parameter is null.
getConstrainedProperties()
returns the PropertyDescriptor
s of the bean properties having at least one constraint or being cascaded (@Valid
annotation).
getConstraintsForMethod()
returns a MethodDescriptor
object describing the method constraints of the given method. The method is uniquely identified by its name and the types of its parameters.
getConstrainedMethods()
returns the MethodDescriptor
s of the methods matching the MethodType
s provided as parameter and having at least one constraint or cascaded parameter or return value.
getConstraintsForConstructor()
returns a ConstructorDescriptor
object describing the method constraints of the given constructor. The constructor is uniquely identified by its name and the types of its parameters.
getConstrainedConstructors()
returns the ConstructorDescriptor
s of the constructors having at least one constraint or cascaded parameter or return value.
7.4. CascadableDescriptor
The CascadableDescriptor
interface describes a cascadable element, i.e. an element which can be marked with @Valid
in order to perform a cascaded validation of the element as described in Graph validation.
CascadableDescriptor
interfacepackage javax.validation.metadata;
/**
* Represents a cascadable element.
*
* @author Gunnar Morling
* @since 1.1
*/
public interface CascadableDescriptor {
/**
* Whether this element is marked for cascaded validation or not.
*
* @return {@code true}, if this element is marked for cascaded validation,
* {@code false} otherwise
*/
boolean isCascaded();
/**
* Returns the group conversions configured for this element.
*
* @return a set containing this element's group conversions; an empty set
* may be returned if no conversions are configured but never
* {@code null}
*/
Set<GroupConversionDescriptor> getGroupConversions();
}
The isCascaded()
method returns true
if the element is marked for cascaded validation.
The method getGroupConversions()
returns a set with the group conversions declared for the cascadable element. An empty set will be returned if no group conversions are configured.
7.5. GroupConversionDescriptor
The GroupConversionDescriptor
interface describes a group conversion rule configured for a cascadable element as described in Group conversion. It is returned by CascadableDescriptor.getGroupConversions()
.
GroupConversionDescriptor
interfacepackage javax.validation.metadata;
/**
* A group conversion rule to be applied during cascaded validation. Two group
* conversion descriptors are considered equal if they have the same
* {@code from} and {@code to} group respectively.
*
* @author Gunnar Morling
* @see ConvertGroup
* @since 1.1
*/
public interface GroupConversionDescriptor {
/**
* Returns the source group of this conversion rule.
*
* @return the source group of this conversion rule
*/
Class<?> getFrom();
/**
* Returns the target group of this conversion rule.
*
* @return the target group of this conversion rule
*/
Class<?> getTo();
}
The getFrom()
method returns the source of a group conversion rule.
The getTo()
method returns the target of a group conversion rule.
7.6. PropertyDescriptor
The PropertyDescriptor
interface describes a constrained property of a Java Bean.
This interface is returned by BeanDescriptor.getConstraintsForProperty(String)
or BeanDescriptor.getConstrainedProperties()
. Constraints declared on the attribute and the getter of the same name according to the JavaBeans rules are returned by this descriptor.
PropertyDescriptor
interfacepackage javax.validation.metadata;
/**
* Describes a Java Bean property hosting validation constraints.
*
* Constraints placed on the attribute and the getter of a given property
* are all referenced.
*
* @author Emmanuel Bernard
*/
public interface PropertyDescriptor extends ElementDescriptor, CascadableDescriptor, ContainerDescriptor {
/**
* Name of the property according to the Java Bean specification.
*
* @return property name
*/
String getPropertyName();
}
getPropertyName()
returns the property name as described in ConstraintViolation.
7.7. ExecutableDescriptor, MethodDescriptor and ConstructorDescriptor
The ExecutableDescriptor
interface describes a constrained method or constructor of a Java type.
ExecutableDescriptor
interfacepackage javax.validation.metadata;
/**
* Provides the common functionality of {@link MethodDescriptor} and
* {@link ConstructorDescriptor}.
*
* @author Gunnar Morling
*
* @since 1.1
*/
public interface ExecutableDescriptor extends ElementDescriptor {
/**
* Returns the method name in case this descriptor represents a method or
* the non-qualified name of the declaring class in case this descriptor
* represents a constructor.
*
* @return the name of the executable represented by this descriptor
*/
String getName();
/**
* Returns a list of descriptors representing this executable's
* parameters, in the order of their declaration, including synthetic
* parameters.
*
* @return a list of descriptors representing this executable's
* parameters; an empty list will be returned if this executable has
* no parameters, but never {@code null}
*/
List<ParameterDescriptor> getParameterDescriptors();
/**
* Returns a descriptor containing the cross-parameter constraints
* of this executable.
*
* @return a descriptor containing the cross-parameter constraints of
* this executable
*/
CrossParameterDescriptor getCrossParameterDescriptor();
/**
* Returns a descriptor for this executable's return value.
* <p>
* An executable without return value will return a descriptor
* representing {@code void}. This descriptor will have no constraint
* associated.
*
* @return a descriptor for this executable's return value
*/
ReturnValueDescriptor getReturnValueDescriptor();
/**
* Returns {@code true} if the executable parameters are constrained either:
* <ul>
* <li>because of a constraint on at least one of the parameters</li>
* <li>because of a cascade on at least one of the parameters (via
* {@link Valid})</li>
* <li>because of at least one cross-parameter constraint</li>
* </ul>
* <p>
* Also returns {@code false} if there is no parameter.
*
* @return {@code true} if the executable parameters are constrained
*/
boolean hasConstrainedParameters();
/**
* Returns {@code true} if the executable return value is constrained
* either:
* <ul>
* <li>because of a constraint on the return value</li>
* <li>because validation is cascaded on the return value (via
* {@link Valid})</li>
* </ul>
* <p>
* Also returns {@code false} if there is no return value.
*
* @return {@code true} if the executable return value is constrained
*/
boolean hasConstrainedReturnValue();
/**
* Returns {@code false}.
* <p>
* An executable per se does not host constraints, use
* {@link #getParameterDescriptors()}, {@link #getCrossParameterDescriptor()}
* and {@link #getReturnValueDescriptor()} to discover constraints.
*
* @return {@code false}
*/
@Override
boolean hasConstraints();
/**
* Returns an empty {@code Set}.
* <p>
* An executable per se does not host constraints, use
* {@link #getParameterDescriptors()}, {@link #getCrossParameterDescriptor()}
* and {@link #getReturnValueDescriptor()} to discover constraints.
*
* @return an empty {@code Set}
*/
@Override
Set<ConstraintDescriptor<?>> getConstraintDescriptors();
/**
* Returns a finder that will always return an empty {@code Set}.
* <p>
* An executable per se does not host constraints, use
* {@link #getParameterDescriptors()}, {@link #getCrossParameterDescriptor()}
* and {@link #getReturnValueDescriptor()} to discover constraints.
*
* @return {@code ConstraintFinder} object
*/
@Override
ConstraintFinder findConstraints();
}
getName()
returns the name of the represented method (e.g. "placeOrder") respectively the non-qualified name of the declaring class of the represented constructor (e.g. "OrderService").
getParameterDescriptors()
returns a list of ParameterDescriptor
s representing the method’s or constructor’s parameters in order of their declaration, including synthetic parameters. An empty list will be returned in case the method or constructor has no parameters.
getCrossParameterDescriptor()
returns a descriptor containing cross-parameter constraints of the method or constructor. If no cross-parameter constraint is present, the descriptor will return an empty set of constraint descriptors.
getReturnValueDescriptor()
returns a descriptor for the method’s or constructor’s return value. A descriptor representing the special class void
, without any constraint descriptors, will be returned for executables which have no return value.
hasConstrainedParameters()
returns true
if any of the parameters is constrained or cascaded or if the represented executable has at least one cross-parameter constraint. Returns false
if there is no parameter.
hasConstrainedReturnValue()
returns true
if the return value is constrained or cascaded. Returns false
if there is no return value.
The methods hasConstraints()
, getConstraintDescriptors()
and findConstraints()
defined on ElementDescriptor
are redefined to clarify that executables do not host constraints directly and thus will always return false
or an empty set of constraints, respectively. Constraint descriptors for individual parameters can be obtained from the corresponding ParameterDescriptor
object, constraint descriptors for cross-parameter constraints can be obtained from the corresponding CrossParameterDescriptor
object and constraint descriptors for the return value can be obtained from ReturnValueDescriptor
.
The interfaces MethodDescriptor
and ConstructorDescriptor
are derived from ExecutableDescriptor
and allow to distinguish between descriptors representing methods and descriptors representing constructors.
MethodDescriptor
interfacepackage javax.validation.metadata;
/**
* Describes a validated method.
*
* @author Gunnar Morling
* @author Emmanuel Bernard
* @since 1.1
*/
public interface MethodDescriptor extends ExecutableDescriptor {
}
ConstructorDescriptor
interfacepackage javax.validation.metadata;
/**
* Describes a validated constructor.
*
* @author Gunnar Morling
* @author Emmanuel Bernard
* @since 1.1
*/
public interface ConstructorDescriptor extends ExecutableDescriptor {
}
MethodDescriptor
objects are returned by BeanDescriptor.getConstraintsForMethod(String, Class<?>…)
and BeanDescriptor.getConstrainedMethods(MethodType, MethodType…)
, while ConstructorDescriptor
objects are returned by BeanDescriptor.getConstraintsForConstructor(Class<?>…)
and BeanDescriptor.getConstrainedConstructors()
.
None of the metadata API methods honor the XML configuration around executable validation nor the presence of @ValidateOnExecution
. In other words, all constrained methods and constructors will be returned by the metadata API regardless of these settings.
7.8. ParameterDescriptor
The ParameterDescriptor
interface describes a constrained parameter of a method or constructor.
This interface is returned by MethodDescriptor.getParameterDescriptors()
and ConstructorDescriptor.getParameterDescriptors()
.
ParameterDescriptor
interfacepackage javax.validation.metadata;
/**
* Describes a validated method or constructor parameter.
*
* @author Gunnar Morling
* @since 1.1
*/
public interface ParameterDescriptor extends ElementDescriptor, CascadableDescriptor,
ContainerDescriptor {
/**
* Returns this parameter's index within the parameter array of the method
* or constructor holding it.
*
* @return this parameter's index
*/
int getIndex();
/**
* Returns this parameter's name as retrieved by the current parameter name
* resolver.
*
* @return this parameter's name
*/
String getName();
}
getIndex()
returns the index of the represented parameter within the parameter array of the method or constructor holding it.
getName()
returns the name of the represented parameter.
7.9. CrossParameterDescriptor
The CrossParameterDescriptor
interface describes an element containing all cross-parameter constraints of a method or constructor.
This interface is returned by MethodDescriptor.getCrossParameterDescriptor()
and ConstructorDescriptor.getCrossParameterDescriptor()
.
CrossParameterDescriptor
interfacepackage javax.validation.metadata;
/**
* Describes an element holding cross-parameter constraints of a method or constructor
*
* @author Emmanuel Bernard
* @since 1.1
*/
public interface CrossParameterDescriptor extends ElementDescriptor {
/**
* @return {@code Object[].class} - the type of the parameter array
*/
@Override
Class<?> getElementClass();
}
getElementClass()
returns Object[]
.
7.10. ReturnValueDescriptor
The ReturnValueDescriptor
interface describes the return value of a method or constructor.
This interface is returned by MethodDescriptor.getReturnValueDescriptor()
and ConstructorDescriptor.getReturnValueDescriptor()
.
ReturnValueDescriptor
interfacepackage javax.validation.metadata;
/**
* Describes a validated return value of a method or constructor.
*
* @author Gunnar Morling
* @since 1.1
*/
public interface ReturnValueDescriptor extends ElementDescriptor, CascadableDescriptor, ContainerDescriptor {
}
7.11. ContainerDescriptor and ContainerElementTypeDescriptor
The ContainerDescriptor
interface describes those elements that can be of a container type, e.g. List
or Map
, and as such may host container element constraints (see Container element constraints) or have container element types that are marked with @Valid
.
ContainerDescriptor
is extended by PropertyDescriptor
, ParameterDescriptor
, ReturnValueDescriptor
and ContainerElementTypeDescriptor
.
ContainerDescriptor
interfacepackage javax.validation.metadata;
/**
* Represents an element that might be a container, thus allowing container element
* constraints.
*
* @author Guillaume Smet
* @since 2.0
*/
public interface ContainerDescriptor {
/**
* If this element is of a container type, e.g. {@code List} or {@code Map}, a set of
* descriptors of those container element types is returned, which are constrained or
* marked with {@link Valid}. A container element type is constrained, if it hosts at
* least one constraint.
* <p>
* In the context of properties and method return values, container element types of
* super-types are considered.
*
* @return the set of descriptors representing the container element types that are
* constrained or are marked with {@code Valid}. An empty set will be returned if this
* element is not of a container type or is of a container type but there are no
* container element types hosting constraints or marked with {@code Valid}.
*/
Set<ContainerElementTypeDescriptor> getConstrainedContainerElementTypes();
}
If a given element is of a container type, getConstrainedContainerElementTypes()
returns a set with descriptors representing those container element types that either host at least one constraint or are marked with @Valid
.
The returned set will be empty if the given element is not of a container type or is of a container type but has no element types that are constrained or marked with @Valid
.
In the context of properties and method return values, container element types of super-types are considered.
The ContainerElementTypeDescriptor
interface describes the potential container element constraints applied to one element type of a container.
This interface is returned by ContainerDescriptor.getConstrainedContainerElementTypes()
.
ContainerElementTypeDescriptor
interfacepackage javax.validation.metadata;
/**
* Describes a validated container element type, e.g. the element type of {@code List} if it
* hosts at least one constraint or is marked with {@link Valid}.
*
* @author Guillaume Smet
* @since 2.0
*/
public interface ContainerElementTypeDescriptor extends ElementDescriptor, CascadableDescriptor, ContainerDescriptor {
/**
* Returns the index of the type argument corresponding to this container element type.
* @return the index of the type argument corresponding to this container element type
*/
Integer getTypeArgumentIndex();
/**
* Returns the container class hosting this container element type.
* @return the container class hosting this container element type
*/
Class<?> getContainerClass();
}
getTypeArgumentIndex()
returns the index of the type argument corresponding to this descriptor instance.
getContainerClass()
returns the type of the container declaring the container element type represented by this descriptor instance.
7.12. ConstraintDescriptor
A ConstraintDescriptor
object describes a given constraint declaration (i.e. a constraint annotation).
ConstraintDescriptor
interfacepackage javax.validation.metadata;
/**
* Describes a single constraint and its composing constraints.
*
* @param <T> the constraint's annotation type
*
* @author Emmanuel Bernard
* @author Hardy Ferentschik
*/
public interface ConstraintDescriptor<T extends Annotation> {
/**
* Returns the annotation describing the constraint declaration.
* If a composing constraint, attribute values are reflecting
* the overridden attributes of the composing constraint
*
* @return the annotation for this constraint
*/
T getAnnotation();
/**
* The non-interpolated error message
*
* @return the non-interpolated error message
*
* @since 1.1
*/
String getMessageTemplate();
/**
* The set of groups the constraint is applied on.
* If the constraint declares no group, a set with only the {@link Default}
* group is returned.
*
* @return the groups the constraint is applied on
*/
Set<Class<?>> getGroups();
/**
* The set of payload the constraint hosts.
*
* @return payload classes hosted on the constraint or an empty set if none
*/
Set<Class<? extends Payload>> getPayload();
/**
* The {@link ConstraintTarget} value of {@code validationAppliesTo} if the constraint
* hosts it or {@code null} otherwise.
*
* @return the {@code ConstraintTarget} value or {@code null}
*
* @since 1.1
*/
ConstraintTarget getValidationAppliesTo();
/**
* List of the constraint validation implementation classes.
*
* @return list of the constraint validation implementation classes
*/
List<Class<? extends ConstraintValidator<T, ?>>> getConstraintValidatorClasses();
/**
* Returns a map containing the annotation attribute names as keys and the
* annotation attribute values as value.
* <p>
* If this constraint is used as part of a composed constraint, attribute
* values are reflecting the overridden attribute of the composing constraint.
*
* @return a map containing the annotation attribute names as keys
* and the annotation attribute values as value
*/
Map<String, Object> getAttributes();
/**
* Return a set of composing {@link ConstraintDescriptor}s where each
* descriptor describes a composing constraint. {@code ConstraintDescriptor}
* instances of composing constraints reflect overridden attribute values in
* {@link #getAttributes()} and {@link #getAnnotation()}.
*
* @return a set of {@code ConstraintDescriptor} objects or an empty set
* in case there are no composing constraints
*/
Set<ConstraintDescriptor<?>> getComposingConstraints();
/**
* @return {@code true} if the constraint is annotated with {@link ReportAsSingleViolation}
*/
boolean isReportAsSingleViolation();
/**
* @return a {@link ValidateUnwrappedValue} describing the unwrapping behavior as given
* via the {@link Unwrapping} constraint payloads.
*
* @since 2.0
*/
ValidateUnwrappedValue getValueUnwrapping();
/**
* Returns an instance of the specified type allowing access to provider-specific APIs.
* <p>
* If the Bean Validation provider implementation does not support the specified class,
* a {@link ValidationException} is thrown.
*
* @param type the class of the object to be returned
* @param <U> the type of the object to be returned
* @return an instance of the specified class
* @throws ValidationException if the provider does not support the call
*
* @since 2.0
*/
<U> U unwrap(Class<U> type);
}
getAnnotation()
returns the annotation instance (or an annotation instance representing the given constraint declaration). If ConstraintDescriptor
represents a composing annotation (see Constraint composition), the returned annotation must reflect parameter overriding. In other words, the annotation parameter values are the overridden values.
getAttributes()
returns a map containing the annotation attribute names as a key, and the annotation attribute values as a value (this API is anticipated to be simpler to use by tools than reflection over the annotation instance). If ConstraintDescriptor()
represents a composing annotation (see Constraint composition), the returned Map
must reflect attribute overriding.
getMessageTemplate()
returns the non-interpolated error message.
getGroups()
returns the groups the constraint is supposed to be applied upon. If no group is set on the constraint declaration, the Default
group is returned. The groups of a composing constraint are the groups of the composed constraint.
getPayload()
returns the payloads associated to the constraint or an empty set if none. The payload from the main constraint annotation is inherited by the composing annotations. Any payload definition on a composing annotation is ignored.
getValidationAppliesTo()
returns the ConstraintTarget
returned by validationAppliesTo
if the constraint hosts the attribute or null
otherwise. The constraint target from the main constraint annotation is inherited by the composing annotation. Any constraint target definition on a composing annotation is ignored.
isReportAsSingleViolation()
returns true
if the constraint is annotated with @ReportAsSingleViolation
.
getComposingConstraints()
return a set of composing ConstraintDescriptor
s where each descriptor describes a composing constraint.
getConstraintValidatorClasses()
returns the ConstraintValidator
classes associated with the constraint.
getValueUnwrapping()
returns a ValidateUnwrappedValue
instance describing the unwrapping behavior.
ValidateUnwrappedValue
enumpackage javax.validation.metadata;
/**
* The unwrapping behavior that can be applied to a specific constraint.
*
* @author Guillaume Smet
* @since 2.0
*/
public enum ValidateUnwrappedValue {
/**
* No specific unwrapping behavior has been defined for this constraint and the default
* behavior applies: if there is exactly one maximally-specific type-compliant
* {@link ValueExtractor} and this extractor is marked with {@link UnwrapByDefault}, this
* extractor is applied and the constraint is applied to the value(s) wrapped by the
* annotated container. Otherwise, no value extractor is applied.
*/
DEFAULT,
/**
* The value is unwrapped before validation, i.e. the constraint is applied to the
* value(s) wrapped by the annotated container.
*/
UNWRAP,
/**
* The value is not unwrapped before validation, i.e. the constraint is applied to the
* annotated element.
*/
SKIP;
}
unwrap()
is provided as a way to access objects of a given type specific to a Bean Validation provider, exposing functionality complementary to the ConstraintDescriptor
contract.
Using this method makes your code non portable.
7.13. Example
Assuming the following constraint definitions
package com.acme.constraint;
@Documented
@Constraint(validatedBy = ValidInterval.Validator.class)
@Target({ METHOD, ANNOTATION_TYPE, CONSTRUCTOR })
@Retention(RUNTIME)
@Repeatable( List.class )
public @interface ValidInterval {
String message() default "{com.acme.constraint.ValidInterval.message}";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
int startParameter();
int endParameter();
@Target({ METHOD, ANNOTATION_TYPE, CONSTRUCTOR })
@Retention(RUNTIME)
@Documented
@interface List {
ValidInterval[] value();
}
@SupportedValidationTarget(PARAMETERS)
class Validator implements ConstraintValidator<ValidInterval, Object[]> {
private int start;
private int end;
@Override
public void initialize(ValidInterval constraintAnnotation) {
this.start = constraintAnnotation.startParameter();
this.end = constraintAnnotation.endParameter();
}
@Override
public boolean isValid(Object[] value, ConstraintValidatorContext context) {
return Integer.parseInt( String.valueOf( value[start] ) ) <
Integer.parseInt( String.valueOf( value[end] ) );
}
}
}
@Documented
@Constraint(validatedBy = ValidAddress.Validator.class)
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable( List.class )
public @interface ValidAddress {
String message() default "{com.acme.constraint.ValidAddress.message}";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
ValidAddress[] value();
}
class Validator implements ConstraintValidator<ValidAddress, Address> {
@Override
public boolean isValid(Address value, ConstraintValidatorContext context) {
// [...]
}
}
}
and the following class definitions
public class Author {
private String firstName;
@NotEmpty(message = "lastname must not be null")
private String lastName;
@Size(max = 30)
private String company;
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public String getCompany() {
return company;
}
public void setCompany(String company) {
this.company = company;
}
}
public class Book {
public interface FirstLevelCheck {
}
public interface SecondLevelCheck {
}
private String title;
private String description;
@Valid
@NotNull
private Author author;
@Valid
public Book(
String title,
@Size(max = 30) String description,
@Valid @ConvertGroup(from = Default.class, to = SecondLevelCheck.class) Author author) {
// [...]
}
public Book() {
// [...]
}
@NotEmpty(groups = { FirstLevelCheck.class, Default.class })
@Size(max = 30)
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public Author getAuthor() {
return author;
}
public void setAuthor(Author author) {
this.author = author;
}
public String getDescription() {
return description;
}
public void setAuthor(String description) {
this.description = description;
}
@ValidInterval(startParameter = 1, endParameter = 2)
public void addChapter(String title, int startPage, int endPage) {
// [...]
}
}
public class Account {
// [...]
}
public class Address {
// [...]
}
public abstract class Roles implements Set<String> {
// [...]
}
public interface LegalEntity {
Iterable<@NotNull String> getRoles();
}
public interface Person extends LegalEntity {
@Override
Set<@NotEmpty String> getRoles();
Map<@NotNull String, @Valid Account> getAccounts();
}
public interface Employee extends Person {
@Override
Set<@NotBlank String> getRoles();
Map<String, List<@NotNull @Valid Address>> getAddresses();
}
public class EmployeeImpl implements Employee {
@Override
public Roles getRoles() {
// [...]
}
@Override
public Map<String, List<@ValidAddress Address>> getAddresses() {
// [...]
}
@Override
public Map<String, Account> getAccounts() {
// [...]
}
}
The following assertions are true.
BeanDescriptor bookDescriptor = validator.getConstraintsForClass(Book.class);
assert ! bookDescriptor.hasConstraints();
assert bookDescriptor.isBeanConstrained();
assert bookDescriptor.getConstrainedMethods( MethodType.NON_GETTER ).size() > 0;
assert bookDescriptor.getConstraintDescriptors().size() == 0; //no bean-level constraint
//more specifically "author", "title" and "keywordsPerChapter"
assert bookDescriptor.getConstrainedProperties().size() == 2;
//not a property
assert bookDescriptor.getConstraintsForProperty( "doesNotExist" ) == null;
//property with no constraint
assert bookDescriptor.getConstraintsForProperty( "description" ) == null;
PropertyDescriptor propertyDescriptor = bookDescriptor.getConstraintsForProperty( "title" );
assert propertyDescriptor.getConstraintDescriptors().size() == 2;
assert "title".equals( propertyDescriptor.getPropertyName() );
//assuming the implementation returns the @NotEmpty constraint first
ConstraintDescriptor<?> constraintDescriptor = propertyDescriptor.getConstraintDescriptors()
.iterator().next();
assert constraintDescriptor.getAnnotation().annotationType().equals( NotEmpty.class );
assert constraintDescriptor.getGroups().size() == 2; //FirstLevelCheck and Default
assert constraintDescriptor.getComposingConstraints().size() == 2;
assert constraintDescriptor.isReportAsSingleViolation() == true;
//@NotEmpty cannot be null
boolean notNullPresence = false;
for ( ConstraintDescriptor<?> composingDescriptor :
constraintDescriptor.getComposingConstraints() ) {
if ( composingDescriptor.getAnnotation().annotationType().equals( NotNull.class ) ) {
notNullPresence = true;
}
}
assert notNullPresence;
//assuming the implementation returns the Size constraint second
constraintDescriptor = propertyDescriptor.getConstraintDescriptors().iterator().next();
assert constraintDescriptor.getAnnotation().annotationType().equals( Size.class );
assert constraintDescriptor.getAttributes().get( "max" ) == Integer.valueOf( 30 );
assert constraintDescriptor.getGroups().size() == 1;
propertyDescriptor = bookDescriptor.getConstraintsForProperty( "author" );
assert propertyDescriptor.getConstraintDescriptors().size() == 1;
assert propertyDescriptor.isCascaded();
//getTitle() and addChapter()
assert bookDescriptor.getConstrainedMethods( MethodType.GETTER, MethodType.NON_GETTER ).size() ==
2;
//the constructor accepting title, description and author
assert bookDescriptor.getConstrainedConstructors().size() == 1;
ConstructorDescriptor constructorDescriptor = bookDescriptor.getConstraintsForConstructor(
String.class, String.class, Author.class
);
assert constructorDescriptor.getName().equals( "Book" );
assert constructorDescriptor.getElementClass() == Book.class;
assert constructorDescriptor.hasConstrainedParameters() == true;
//return value is marked for cascaded validation
assert constructorDescriptor.hasConstrainedReturnValue() == true;
//constraints are retrieved via the sub-descriptors for parameters etc.
assert constructorDescriptor.hasConstraints() == false;
//one descriptor for each parameter
assert constructorDescriptor.getParameterDescriptors().size() == 3;
//"description" parameter
ParameterDescriptor parameterDescriptor = constructorDescriptor.getParameterDescriptors()
.get( 1 );
//assuming the default parameter name provider is used and parameter names can
//be obtained
assert parameterDescriptor.getName().equals( "description" );
assert parameterDescriptor.getElementClass() == String.class;
assert parameterDescriptor.getIndex() == 1;
assert parameterDescriptor.hasConstraints() == true;
Set<ConstraintDescriptor<?>> parameterConstraints =
parameterDescriptor.getConstraintDescriptors();
assert parameterConstraints.iterator().next().getAnnotation().annotationType() == Size.class;
//"author" parameter
parameterDescriptor = constructorDescriptor.getParameterDescriptors().get( 2 );
assert parameterDescriptor.hasConstraints() == false;
assert parameterDescriptor.isCascaded() == true;
//group conversion on "author" parameter
GroupConversionDescriptor groupConversion =
parameterDescriptor.getGroupConversions().iterator().next();
assert groupConversion.getFrom() == Default.class;
assert groupConversion.getTo() == SecondLevelCheck.class;
//constructor return value
ReturnValueDescriptor returnValueDescriptor = constructorDescriptor.getReturnValueDescriptor();
assert returnValueDescriptor.hasConstraints() == false;
assert returnValueDescriptor.isCascaded() == true;
//a getter is also a method which is constrained on its return value
MethodDescriptor methodDescriptor = bookDescriptor.getConstraintsForMethod( "getTitle" );
assert methodDescriptor.getName().equals( "getTitle" );
assert methodDescriptor.getElementClass() == String.class;
assert methodDescriptor.hasConstrainedParameters() == false;
assert methodDescriptor.hasConstrainedReturnValue() == true;
assert methodDescriptor.hasConstraints() == false;
returnValueDescriptor = methodDescriptor.getReturnValueDescriptor();
assert returnValueDescriptor.getElementClass() == String.class;
assert returnValueDescriptor.getConstraintDescriptors().size() == 2;
assert returnValueDescriptor.isCascaded() == false;
//void method which has a cross-parameter constraint
methodDescriptor = bookDescriptor.getConstraintsForMethod(
"addChapter", String.class, int.class, int.class
);
assert methodDescriptor.getElementClass() == void.class;
assert methodDescriptor.hasConstrainedParameters() == true;
assert methodDescriptor.hasConstrainedReturnValue() == false;
//cross-parameter constraints accessible via separate descriptor
assert methodDescriptor.hasConstraints() == false;
assert methodDescriptor.getReturnValueDescriptor().getElementClass() == void.class;
//cross-parameter descriptor
CrossParameterDescriptor crossParameterDescriptor =
methodDescriptor.getCrossParameterDescriptor();
assert crossParameterDescriptor.getElementClass() == Object[].class;
assert crossParameterDescriptor.hasConstraints() == true;
ConstraintDescriptor<?> crossParameterConstraint =
crossParameterDescriptor.getConstraintDescriptors().iterator().next();
assert crossParameterConstraint.getAnnotation().annotationType() == ValidInterval.class;
// no constrained container element types for title
assert bookDescriptor.getConstraintsForProperty( "title" )
.getConstrainedContainerElementTypes().size() == 0;
BeanDescriptor employeeImplDescriptor = validator.getConstraintsForClass( Employee.class );
// container element constraints for property "roles"
PropertyDescriptor rolesDescriptor = employeeImplDescriptor.getConstraintsForProperty( "roles" );
assert rolesDescriptor != null;
Set<ContainerElementTypeDescriptor> constrainedContainerElementTypes = rolesDescriptor
.getConstrainedContainerElementTypes();
// the container element types of Set and Iterable; Roles does not declare any container element types itself
assert constrainedContainerElementTypes.size() == 2;
Iterator<ContainerElementTypeDescriptor> it = constrainedContainerElementTypes.iterator();
// assuming that the descriptor for Set is returned first
ContainerElementTypeDescriptor containerElementTypeDescriptor = it.next();
assert containerElementTypeDescriptor.getContainerClass() == Set.class;
assert containerElementTypeDescriptor.getTypeArgumentIndex() == 0;
assert containerElementTypeDescriptor.getElementClass() == String.class;
// @NotEmpty and @NotBlank
assert containerElementTypeDescriptor.getConstraintDescriptors().size() == 2;
// assuming that the descriptor for Iterable is returned next
containerElementTypeDescriptor = it.next();
assert containerElementTypeDescriptor.getContainerClass() == Iterable.class;
assert containerElementTypeDescriptor.getTypeArgumentIndex() == 0;
assert containerElementTypeDescriptor.getElementClass() == String.class;
// @NotNull
assert containerElementTypeDescriptor.getConstraintDescriptors().size() == 1;
// container element constraints for property "accounts"
PropertyDescriptor accountsDescriptor = employeeImplDescriptor
.getConstraintsForProperty( "accounts" );
constrainedContainerElementTypes = accountsDescriptor.getConstrainedContainerElementTypes();
// the map key type and the map value type
assert constrainedContainerElementTypes.size() == 2;
it = constrainedContainerElementTypes.iterator();
// assuming that the descriptor for the map key is returned first
containerElementTypeDescriptor = it.next();
assert containerElementTypeDescriptor.getContainerClass() == Map.class;
assert containerElementTypeDescriptor.getTypeArgumentIndex() == 0;
assert containerElementTypeDescriptor.getElementClass() == String.class;
// @NotNull
assert containerElementTypeDescriptor.getConstraintDescriptors().size() == 1;
assert containerElementTypeDescriptor.isCascaded() == false;
// assuming that the descriptor for the map value is returned next
containerElementTypeDescriptor = it.next();
assert containerElementTypeDescriptor.getContainerClass() == Map.class;
assert containerElementTypeDescriptor.getTypeArgumentIndex() == 1;
assert containerElementTypeDescriptor.getElementClass() == Account.class;
assert containerElementTypeDescriptor.getConstraintDescriptors().size() == 0;
assert containerElementTypeDescriptor.isCascaded() == true;
// container element constraints for property "addresses"
PropertyDescriptor addressesDescriptor = employeeImplDescriptor
.getConstraintsForProperty( "addresses" );
constrainedContainerElementTypes = addressesDescriptor.getConstrainedContainerElementTypes();
// the map value type
assert constrainedContainerElementTypes.size() == 1;
it = constrainedContainerElementTypes.iterator();
containerElementTypeDescriptor = it.next();
assert containerElementTypeDescriptor.getContainerClass() == Map.class;
assert containerElementTypeDescriptor.getTypeArgumentIndex() == 1;
assert containerElementTypeDescriptor.getElementClass() == List.class;
// No constraints nor @Valid on List itself
assert containerElementTypeDescriptor.getConstraintDescriptors().size() == 0;
assert containerElementTypeDescriptor.isCascaded() == false;
// container element type of the nested List container
constrainedContainerElementTypes = containerElementTypeDescriptor.getConstrainedContainerElementTypes();
assert constrainedContainerElementTypes.size() == 1;
it = constrainedContainerElementTypes.iterator();
containerElementTypeDescriptor = it.next();
assert containerElementTypeDescriptor.getContainerClass() == List.class;
assert containerElementTypeDescriptor.getTypeArgumentIndex() == 0;
assert containerElementTypeDescriptor.getElementClass() == Address.class;
// @NotNull and @ValidAddress
assert containerElementTypeDescriptor.getConstraintDescriptors().size() == 2;
assert containerElementTypeDescriptor.isCascaded() == true;
8. Built-in Constraint definitions
The specification defines a small set of built-in constraints. Their usage is encouraged both in regular constraint declarations and as composing constraints. Using this set of constraints will enhance portability of your constraints across constraint-consuming frameworks relying on the metadata API (such as client side validation frameworks or database schema generation frameworks).
Built-in annotations are annotated with an empty @Constraint
annotation to avoid any dependency between the specification API and a specific implementation. Each Bean Validation provider must recognize built-in constraint annotations as valid constraint definitions and provide compliant constraint implementations for each. The built-in constraint validation implementation is having a lower priority than an XML mapping definition. In other words ConstraintValidator
implementations for built-in constraints can be overridden by using the XML mapping (see Overriding constraint definitions in XML).
All built-in constraints are in the javax.validation.constraints
package. Here is the list of constraints and their declaration.
8.1. @Null
constraint
@Null
constraintpackage javax.validation.constraints;
/**
* The annotated element must be {@code null}.
* Accepts any type.
*
* @author Emmanuel Bernard
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
@Documented
@Constraint(validatedBy = { })
public @interface Null {
String message() default "{javax.validation.constraints.Null.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
/**
* Defines several {@link Null} annotations on the same element.
*
* @see javax.validation.constraints.Null
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
Null[] value();
}
}
8.2. @NotNull
constraint
@NotNull
constraintpackage javax.validation.constraints;
/**
* The annotated element must not be {@code null}.
* Accepts any type.
*
* @author Emmanuel Bernard
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
@Documented
@Constraint(validatedBy = { })
public @interface NotNull {
String message() default "{javax.validation.constraints.NotNull.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
/**
* Defines several {@link NotNull} annotations on the same element.
*
* @see javax.validation.constraints.NotNull
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
NotNull[] value();
}
}
8.3. @AssertTrue
constraint
@AssertTrue
constraintpackage javax.validation.constraints;
/**
* The annotated element must be true.
* Supported types are {@code boolean} and {@code Boolean}.
* <p>
* {@code null} elements are considered valid.
*
* @author Emmanuel Bernard
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
@Documented
@Constraint(validatedBy = { })
public @interface AssertTrue {
String message() default "{javax.validation.constraints.AssertTrue.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
/**
* Defines several {@link AssertTrue} annotations on the same element.
*
* @see AssertTrue
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
AssertTrue[] value();
}
}
8.4. @AssertFalse
constraint
@AssertFalse
constraintpackage javax.validation.constraints;
/**
* The annotated element must be false.
* Supported types are {@code boolean} and {@code Boolean}.
* <p>
* {@code null} elements are considered valid.
*
* @author Emmanuel Bernard
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
@Documented
@Constraint(validatedBy = { })
public @interface AssertFalse {
String message() default "{javax.validation.constraints.AssertFalse.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
/**
* Defines several {@link AssertFalse} annotations on the same element.
*
* @see javax.validation.constraints.AssertFalse
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
AssertFalse[] value();
}
}
8.5. @Min
constraint
@Min
constraintpackage javax.validation.constraints;
/**
* The annotated element must be a number whose value must be higher or
* equal to the specified minimum.
* <p>
* Supported types are:
* <ul>
* <li>{@code BigDecimal}</li>
* <li>{@code BigInteger}</li>
* <li>{@code byte}, {@code short}, {@code int}, {@code long}, and their respective
* wrappers</li>
* </ul>
* Note that {@code double} and {@code float} are not supported due to rounding errors
* (some providers might provide some approximative support).
* <p>
* {@code null} elements are considered valid.
*
* @author Emmanuel Bernard
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
@Documented
@Constraint(validatedBy = { })
public @interface Min {
String message() default "{javax.validation.constraints.Min.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
/**
* @return value the element must be higher or equal to
*/
long value();
/**
* Defines several {@link Min} annotations on the same element.
*
* @see Min
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
Min[] value();
}
}
8.6. @Max
constraint
@Max
constraintpackage javax.validation.constraints;
/**
* The annotated element must be a number whose value must be lower or
* equal to the specified maximum.
* <p>
* Supported types are:
* <ul>
* <li>{@code BigDecimal}</li>
* <li>{@code BigInteger}</li>
* <li>{@code byte}, {@code short}, {@code int}, {@code long}, and their respective
* wrappers</li>
* </ul>
* Note that {@code double} and {@code float} are not supported due to rounding errors
* (some providers might provide some approximative support).
* <p>
* {@code null} elements are considered valid.
*
* @author Emmanuel Bernard
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
@Documented
@Constraint(validatedBy = { })
public @interface Max {
String message() default "{javax.validation.constraints.Max.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
/**
* @return value the element must be lower or equal to
*/
long value();
/**
* Defines several {@link Max} annotations on the same element.
*
* @see Max
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
Max[] value();
}
}
8.7. @DecimalMin
constraint
@DecimalMin
constraintpackage javax.validation.constraints;
/**
* The annotated element must be a number whose value must be higher or
* equal to the specified minimum.
* <p>
* Supported types are:
* <ul>
* <li>{@code BigDecimal}</li>
* <li>{@code BigInteger}</li>
* <li>{@code CharSequence}</li>
* <li>{@code byte}, {@code short}, {@code int}, {@code long}, and their respective
* wrappers</li>
* </ul>
* Note that {@code double} and {@code float} are not supported due to rounding errors
* (some providers might provide some approximative support).
* <p>
* {@code null} elements are considered valid.
*
* @author Emmanuel Bernard
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
@Documented
@Constraint(validatedBy = { })
public @interface DecimalMin {
String message() default "{javax.validation.constraints.DecimalMin.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
/**
* The {@code String} representation of the min value according to the
* {@code BigDecimal} string representation.
*
* @return value the element must be higher or equal to
*/
String value();
/**
* Specifies whether the specified minimum is inclusive or exclusive.
* By default, it is inclusive.
*
* @return {@code true} if the value must be higher or equal to the specified minimum,
* {@code false} if the value must be higher
*
* @since 1.1
*/
boolean inclusive() default true;
/**
* Defines several {@link DecimalMin} annotations on the same element.
*
* @see DecimalMin
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
DecimalMin[] value();
}
}
8.8. @DecimalMax
constraint
@DecimalMax
constraintpackage javax.validation.constraints;
/**
* The annotated element must be a number whose value must be lower or
* equal to the specified maximum.
* <p>
* Supported types are:
* <ul>
* <li>{@code BigDecimal}</li>
* <li>{@code BigInteger}</li>
* <li>{@code CharSequence}</li>
* <li>{@code byte}, {@code short}, {@code int}, {@code long}, and their respective
* wrappers</li>
* </ul>
* Note that {@code double} and {@code float} are not supported due to rounding errors
* (some providers might provide some approximative support).
* <p>
* {@code null} elements are considered valid.
*
* @author Emmanuel Bernard
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
@Documented
@Constraint(validatedBy = { })
public @interface DecimalMax {
String message() default "{javax.validation.constraints.DecimalMax.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
/**
* The {@code String} representation of the max value according to the
* {@code BigDecimal} string representation.
*
* @return value the element must be lower or equal to
*/
String value();
/**
* Specifies whether the specified maximum is inclusive or exclusive.
* By default, it is inclusive.
*
* @return {@code true} if the value must be lower or equal to the specified maximum,
* {@code false} if the value must be lower
*
* @since 1.1
*/
boolean inclusive() default true;
/**
* Defines several {@link DecimalMax} annotations on the same element.
*
* @see DecimalMax
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
DecimalMax[] value();
}
}
8.9. @Negative
constraint
@Negative
constraintpackage javax.validation.constraints;
/**
* The annotated element must be a strictly negative number (i.e. 0 is considered as an
* invalid value).
* <p>
* Supported types are:
* <ul>
* <li>{@code BigDecimal}</li>
* <li>{@code BigInteger}</li>
* <li>{@code byte}, {@code short}, {@code int}, {@code long}, {@code float},
* {@code double} and their respective wrappers</li>
* </ul>
* <p>
* {@code null} elements are considered valid.
*
* @author Gunnar Morling
* @since 2.0
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
@Documented
@Constraint(validatedBy = { })
public @interface Negative {
String message() default "{javax.validation.constraints.Negative.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
/**
* Defines several {@link Negative} constraints on the same element.
*
* @see Negative
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
Negative[] value();
}
}
8.10. @NegativeOrZero
constraint
@NegativeOrZero
constraintpackage javax.validation.constraints;
/**
* The annotated element must be a negative number or 0.
* <p>
* Supported types are:
* <ul>
* <li>{@code BigDecimal}</li>
* <li>{@code BigInteger}</li>
* <li>{@code byte}, {@code short}, {@code int}, {@code long}, {@code float},
* {@code double} and their respective wrappers</li>
* </ul>
* <p>
* {@code null} elements are considered valid.
*
* @author Gunnar Morling
* @since 2.0
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
@Documented
@Constraint(validatedBy = { })
public @interface NegativeOrZero {
String message() default "{javax.validation.constraints.NegativeOrZero.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
/**
* Defines several {@link NegativeOrZero} constraints on the same element.
*
* @see NegativeOrZero
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
NegativeOrZero[] value();
}
}
8.11. @Positive
constraint
@Positive
constraintpackage javax.validation.constraints;
/**
* The annotated element must be a strictly positive number (i.e. 0 is considered as an
* invalid value).
* <p>
* Supported types are:
* <ul>
* <li>{@code BigDecimal}</li>
* <li>{@code BigInteger}</li>
* <li>{@code byte}, {@code short}, {@code int}, {@code long}, {@code float},
* {@code double} and their respective wrappers</li>
* </ul>
* <p>
* {@code null} elements are considered valid.
*
* @author Gunnar Morling
* @since 2.0
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
@Documented
@Constraint(validatedBy = { })
public @interface Positive {
String message() default "{javax.validation.constraints.Positive.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
/**
* Defines several {@link Positive} constraints on the same element.
*
* @see Positive
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
Positive[] value();
}
}
8.12. @PositiveOrZero
constraint
@PositiveOrZero
constraintpackage javax.validation.constraints;
/**
* The annotated element must be a positive number or 0.
* <p>
* Supported types are:
* <ul>
* <li>{@code BigDecimal}</li>
* <li>{@code BigInteger}</li>
* <li>{@code byte}, {@code short}, {@code int}, {@code long}, {@code float},
* {@code double} and their respective wrappers</li>
* </ul>
* <p>
* {@code null} elements are considered valid.
*
* @author Gunnar Morling
* @since 2.0
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
@Documented
@Constraint(validatedBy = { })
public @interface PositiveOrZero {
String message() default "{javax.validation.constraints.PositiveOrZero.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
/**
* Defines several {@link PositiveOrZero} constraints on the same element.
*
* @see PositiveOrZero
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
PositiveOrZero[] value();
}
}
8.13. @Size
constraint
@Size
constraintpackage javax.validation.constraints;
/**
* The annotated element size must be between the specified boundaries (included).
* <p>
* Supported types are:
* <ul>
* <li>{@code CharSequence} (length of character sequence is evaluated)</li>
* <li>{@code Collection} (collection size is evaluated)</li>
* <li>{@code Map} (map size is evaluated)</li>
* <li>Array (array length is evaluated)</li>
* </ul>
* <p>
* {@code null} elements are considered valid.
*
* @author Emmanuel Bernard
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
@Documented
@Constraint(validatedBy = { })
public @interface Size {
String message() default "{javax.validation.constraints.Size.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
/**
* @return size the element must be higher or equal to
*/
int min() default 0;
/**
* @return size the element must be lower or equal to
*/
int max() default Integer.MAX_VALUE;
/**
* Defines several {@link Size} annotations on the same element.
*
* @see Size
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
Size[] value();
}
}
8.14. @Digits
constraint
@Digits
constraintpackage javax.validation.constraints;
/**
* The annotated element must be a number within accepted range
* Supported types are:
* <ul>
* <li>{@code BigDecimal}</li>
* <li>{@code BigInteger}</li>
* <li>{@code CharSequence}</li>
* <li>{@code byte}, {@code short}, {@code int}, {@code long}, and their respective
* wrapper types</li>
* </ul>
* <p>
* {@code null} elements are considered valid.
*
* @author Emmanuel Bernard
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
@Documented
@Constraint(validatedBy = { })
public @interface Digits {
String message() default "{javax.validation.constraints.Digits.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
/**
* @return maximum number of integral digits accepted for this number
*/
int integer();
/**
* @return maximum number of fractional digits accepted for this number
*/
int fraction();
/**
* Defines several {@link Digits} annotations on the same element.
*
* @see Digits
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
Digits[] value();
}
}
8.15. @Past
constraint
@Past
constraintpackage javax.validation.constraints;
/**
* The annotated element must be an instant, date or time in the past.
* <p>
* <i>Now</i> is defined by the {@link ClockProvider} attached to the {@link Validator} or
* {@link ValidatorFactory}. The default {@code clockProvider} defines the current time
* according to the virtual machine, applying the current default time zone if needed.
* <p>
* Supported types are:
* <ul>
* <li>{@code java.util.Date}</li>
* <li>{@code java.util.Calendar}</li>
* <li>{@code java.time.Instant}</li>
* <li>{@code java.time.LocalDate}</li>
* <li>{@code java.time.LocalDateTime}</li>
* <li>{@code java.time.LocalTime}</li>
* <li>{@code java.time.MonthDay}</li>
* <li>{@code java.time.OffsetDateTime}</li>
* <li>{@code java.time.OffsetTime}</li>
* <li>{@code java.time.Year}</li>
* <li>{@code java.time.YearMonth}</li>
* <li>{@code java.time.ZonedDateTime}</li>
* <li>{@code java.time.chrono.HijrahDate}</li>
* <li>{@code java.time.chrono.JapaneseDate}</li>
* <li>{@code java.time.chrono.MinguoDate}</li>
* <li>{@code java.time.chrono.ThaiBuddhistDate}</li>
* </ul>
* <p>
* {@code null} elements are considered valid.
*
* @author Emmanuel Bernard
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
@Documented
@Constraint(validatedBy = { })
public @interface Past {
String message() default "{javax.validation.constraints.Past.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
/**
* Defines several {@link Past} annotations on the same element.
*
* @see Past
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
Past[] value();
}
}
8.16. @PastOrPresent
constraint
@PastOrPresent
constraintpackage javax.validation.constraints;
/**
* The annotated element must be an instant, date or time in the past or in the present.
* <p>
* <i>Now</i> is defined by the {@link ClockProvider} attached to the {@link Validator} or
* {@link ValidatorFactory}. The default {@code clockProvider} defines the current time
* according to the virtual machine, applying the current default time zone if needed.
* <p>
* The notion of present is defined relatively to the type on which the constraint is
* used. For instance, if the constraint is on a {@link Year}, present would mean the whole
* current year.
* <p>
* Supported types are:
* <ul>
* <li>{@code java.util.Date}</li>
* <li>{@code java.util.Calendar}</li>
* <li>{@code java.time.Instant}</li>
* <li>{@code java.time.LocalDate}</li>
* <li>{@code java.time.LocalDateTime}</li>
* <li>{@code java.time.LocalTime}</li>
* <li>{@code java.time.MonthDay}</li>
* <li>{@code java.time.OffsetDateTime}</li>
* <li>{@code java.time.OffsetTime}</li>
* <li>{@code java.time.Year}</li>
* <li>{@code java.time.YearMonth}</li>
* <li>{@code java.time.ZonedDateTime}</li>
* <li>{@code java.time.chrono.HijrahDate}</li>
* <li>{@code java.time.chrono.JapaneseDate}</li>
* <li>{@code java.time.chrono.MinguoDate}</li>
* <li>{@code java.time.chrono.ThaiBuddhistDate}</li>
* </ul>
* <p>
* {@code null} elements are considered valid.
*
* @author Guillaume Smet
* @since 2.0
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
@Documented
@Constraint(validatedBy = { })
public @interface PastOrPresent {
String message() default "{javax.validation.constraints.PastOrPresent.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
/**
* Defines several {@link PastOrPresent} annotations on the same element.
*
* @see PastOrPresent
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
PastOrPresent[] value();
}
}
8.17. @Future
constraint
@Future
constraintpackage javax.validation.constraints;
/**
* The annotated element must be an instant, date or time in the future.
* <p>
* <i>Now</i> is defined by the {@link ClockProvider} attached to the {@link Validator} or
* {@link ValidatorFactory}. The default {@code clockProvider} defines the current time
* according to the virtual machine, applying the current default time zone if needed.
* <p>
* Supported types are:
* <ul>
* <li>{@code java.util.Date}</li>
* <li>{@code java.util.Calendar}</li>
* <li>{@code java.time.Instant}</li>
* <li>{@code java.time.LocalDate}</li>
* <li>{@code java.time.LocalDateTime}</li>
* <li>{@code java.time.LocalTime}</li>
* <li>{@code java.time.MonthDay}</li>
* <li>{@code java.time.OffsetDateTime}</li>
* <li>{@code java.time.OffsetTime}</li>
* <li>{@code java.time.Year}</li>
* <li>{@code java.time.YearMonth}</li>
* <li>{@code java.time.ZonedDateTime}</li>
* <li>{@code java.time.chrono.HijrahDate}</li>
* <li>{@code java.time.chrono.JapaneseDate}</li>
* <li>{@code java.time.chrono.MinguoDate}</li>
* <li>{@code java.time.chrono.ThaiBuddhistDate}</li>
* </ul>
* <p>
* {@code null} elements are considered valid.
*
* @author Emmanuel Bernard
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
@Documented
@Constraint(validatedBy = { })
public @interface Future {
String message() default "{javax.validation.constraints.Future.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
/**
* Defines several {@link Future} annotations on the same element.
*
* @see Future
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
Future[] value();
}
}
8.18. @FutureOrPresent
constraint
@FutureOrPresent
constraintpackage javax.validation.constraints;
/**
* The annotated element must be an instant, date or time in the present or in the future.
* <p>
* <i>Now</i> is defined by the {@link ClockProvider} attached to the {@link Validator} or
* {@link ValidatorFactory}. The default {@code clockProvider} defines the current time
* according to the virtual machine, applying the current default time zone if needed.
* <p>
* The notion of present here is defined relatively to the type on which the constraint is
* used. For instance, if the constraint is on a {@link Year}, present would mean the whole
* current year.
* <p>
* Supported types are:
* <ul>
* <li>{@code java.util.Date}</li>
* <li>{@code java.util.Calendar}</li>
* <li>{@code java.time.Instant}</li>
* <li>{@code java.time.LocalDate}</li>
* <li>{@code java.time.LocalDateTime}</li>
* <li>{@code java.time.LocalTime}</li>
* <li>{@code java.time.MonthDay}</li>
* <li>{@code java.time.OffsetDateTime}</li>
* <li>{@code java.time.OffsetTime}</li>
* <li>{@code java.time.Year}</li>
* <li>{@code java.time.YearMonth}</li>
* <li>{@code java.time.ZonedDateTime}</li>
* <li>{@code java.time.chrono.HijrahDate}</li>
* <li>{@code java.time.chrono.JapaneseDate}</li>
* <li>{@code java.time.chrono.MinguoDate}</li>
* <li>{@code java.time.chrono.ThaiBuddhistDate}</li>
* </ul>
* <p>
* {@code null} elements are considered valid.
*
* @author Guillaume Smet
* @since 2.0
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
@Documented
@Constraint(validatedBy = { })
public @interface FutureOrPresent {
String message() default "{javax.validation.constraints.FutureOrPresent.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
/**
* Defines several {@link FutureOrPresent} annotations on the same element.
*
* @see FutureOrPresent
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
FutureOrPresent[] value();
}
}
8.19. @Pattern
constraint
@Pattern
constraintpackage javax.validation.constraints;
/**
* The annotated {@code CharSequence} must match the specified regular expression.
* The regular expression follows the Java regular expression conventions
* see {@link java.util.regex.Pattern}.
* <p>
* Accepts {@code CharSequence}. {@code null} elements are considered valid.
*
* @author Emmanuel Bernard
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
@Documented
@Constraint(validatedBy = { })
public @interface Pattern {
/**
* @return the regular expression to match
*/
String regexp();
/**
* @return array of {@code Flag}s considered when resolving the regular expression
*/
Flag[] flags() default { };
/**
* @return the error message template
*/
String message() default "{javax.validation.constraints.Pattern.message}";
/**
* @return the groups the constraint belongs to
*/
Class<?>[] groups() default { };
/**
* @return the payload associated to the constraint
*/
Class<? extends Payload>[] payload() default { };
/**
* Possible Regexp flags.
*/
public static enum Flag {
/**
* Enables Unix lines mode.
*
* @see java.util.regex.Pattern#UNIX_LINES
*/
UNIX_LINES( java.util.regex.Pattern.UNIX_LINES ),
/**
* Enables case-insensitive matching.
*
* @see java.util.regex.Pattern#CASE_INSENSITIVE
*/
CASE_INSENSITIVE( java.util.regex.Pattern.CASE_INSENSITIVE ),
/**
* Permits whitespace and comments in pattern.
*
* @see java.util.regex.Pattern#COMMENTS
*/
COMMENTS( java.util.regex.Pattern.COMMENTS ),
/**
* Enables multiline mode.
*
* @see java.util.regex.Pattern#MULTILINE
*/
MULTILINE( java.util.regex.Pattern.MULTILINE ),
/**
* Enables dotall mode.
*
* @see java.util.regex.Pattern#DOTALL
*/
DOTALL( java.util.regex.Pattern.DOTALL ),
/**
* Enables Unicode-aware case folding.
*
* @see java.util.regex.Pattern#UNICODE_CASE
*/
UNICODE_CASE( java.util.regex.Pattern.UNICODE_CASE ),
/**
* Enables canonical equivalence.
*
* @see java.util.regex.Pattern#CANON_EQ
*/
CANON_EQ( java.util.regex.Pattern.CANON_EQ );
//JDK flag value
private final int value;
private Flag(int value) {
this.value = value;
}
/**
* @return flag value as defined in {@link java.util.regex.Pattern}
*/
public int getValue() {
return value;
}
}
/**
* Defines several {@link Pattern} annotations on the same element.
*
* @see Pattern
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
Pattern[] value();
}
}
8.20. @NotEmpty
constraint
@NotEmpty
constraintpackage javax.validation.constraints;
/**
* The annotated element must not be {@code null} nor empty. Supported types are:
* <ul>
* <li>{@code CharSequence} (length of character sequence is evaluated)</li>
* <li>{@code Collection} (collection size is evaluated)</li>
* <li>{@code Map} (map size is evaluated)</li>
* <li>Array (array length is evaluated)</li>
* </ul>
*
* @author Emmanuel Bernard
* @author Hardy Ferentschik
*
* @since 2.0
*/
@Documented
@Constraint(validatedBy = { })
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
public @interface NotEmpty {
String message() default "{javax.validation.constraints.NotEmpty.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
/**
* Defines several {@code @NotEmpty} constraints on the same element.
*
* @see NotEmpty
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
public @interface List {
NotEmpty[] value();
}
}
8.21. @NotBlank
constraint
@NotBlank
constraintpackage javax.validation.constraints;
/**
* The annotated element must not be {@code null} and must contain at least one
* non-whitespace character. Accepts {@code CharSequence}.
*
* @author Hardy Ferentschik
* @since 2.0
*
* @see Character#isWhitespace(char)
*/
@Documented
@Constraint(validatedBy = { })
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
public @interface NotBlank {
String message() default "{javax.validation.constraints.NotBlank.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
/**
* Defines several {@code @NotBlank} constraints on the same element.
*
* @see NotBlank
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
public @interface List {
NotBlank[] value();
}
}
8.22. @Email
constraint
@Email
constraintpackage javax.validation.constraints;
/**
* The string has to be a well-formed email address. Exact semantics of what makes up a valid
* email address are left to Bean Validation providers. Accepts {@code CharSequence}.
*
* @author Emmanuel Bernard
* @author Hardy Ferentschik
*
* @since 2.0
*/
@Documented
@Constraint(validatedBy = { })
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
public @interface Email {
String message() default "{javax.validation.constraints.Email.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
/**
* @return an additional regular expression the annotated element must match. The default
* is any string ('.*')
*/
String regexp() default ".*";
/**
* @return used in combination with {@link #regexp()} in order to specify a regular
* expression option
*/
Pattern.Flag[] flags() default { };
/**
* Defines several {@code @Email} constraints on the same element.
*
* @see Email
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
public @interface List {
Email[] value();
}
}
9. XML deployment descriptor
Two kinds of XML descriptors are used by Bean Validation. The first one describes the Bean Validation configuration provided as META-INF/validation.xml
. The second one describes constraints declarations and closely matches the annotations declaration approach. If an XML descriptor does not validate against the corresponding XSD file, a ValidationException
is raised.
9.1. Constraint definition and declaration
Bean Validation lets you declare constraints via XML rather than annotations. You can either ignore constraints declared via annotations or consider XML as adding additional constraints on top of annotation constraints. While it is not possible to define a new constraint via XML, you can redefine the list of ConstraintValidator
classes associated to a given constraint definition.
There is no distinction between an annotation based constraint declaration and an XML based constraint declaration: they are considered equivalent and should be treated as such by the Bean Validation provider. The rest of the specification only refers to annotations as validation metadata: it should be read as annotation or their XML descriptor equivalent.
Specifically when exploring metadata, the Bean Validation provider must ensure that an annotation instance corresponding to the XML declaration is provided via ConstraintDescriptor.getAnnnotation()
. The annotation elements as well as ConstraintValidator.getAttributes()
must reflect the values described in the XML declaration (see Converting the string representation of a value). Likewise, ConstraintDescriptor.getConstraintValidatorClasses()
must reflect XML based constraint definition overriding (see Overriding constraint definitions in XML).
A given class must not be described more than once among all the XML mapping descriptors. A given field or getter must not be described more than once on a given class description. A given constraint definition must not be overridden more than once among all the XML mapping descriptors. If any of these rules is violated in a given validation deployment, a ValidationException
is raised during the creation of the ValidatorFactory
.
The schema is provided in XML Schema.
9.1.1. Constraint declaration in XML
If default-package
is set, all unqualified class names (including annotations) are considered part of the package described by default-package
.
A given JavaBean is described by the bean
element. The name of the class is mandatory. By default, all constraint declarations expressed via annotations are ignored for classes described in XML. You can force Bean Validation to consider both annotations and XML constraint declarations by using ignore-annotations="false"
on bean
.
Note
|
The |
If the name of the class does refer to a class not present in the classpath, a ValidationException
is raised.
<?xml version="1.0" encoding="UTF-8"?>
<constraint-mappings
xmlns="http://xmlns.jcp.org/xml/ns/validation/mapping"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/validation/mapping
http://xmlns.jcp.org/xml/ns/validation/mapping/validation-mapping-2.0.xsd"
version="2.0">
<default-package>com.acme.app.domain</default-package>
<bean class="Customer" ignore-annotations="false">
[...]
</bean>
<bean class="com.acme.common.model.Address">
[...]
</bean>
</constraint-mappings>
9.1.1.1. Class-level overriding
Class level annotations are described via the class
element. If ignore-annotations
is declared, Bean Validation must honor the explicit value for this element. If not declared, the default value defined in the encapsulating bean
element is considered.
When ignore-annotations
is true, class-level Bean Validation annotations are ignored for this class (including the @GroupSequence
). When ignore-annotations
is false:
-
Constraints declared in XML and constraints declared in annotations are added and form the list of class-level declared constraints.
-
@GroupSequence
is considered unlessgroup-sequence
element is explicitly used.
<?xml version="1.0" encoding="UTF-8"?>
<constraint-mappings
xmlns="http://xmlns.jcp.org/xml/ns/validation/mapping"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/validation/mapping
http://xmlns.jcp.org/xml/ns/validation/mapping/validation-mapping-2.0.xsd"
version="2.0">
<default-package>com.acme.app.domain</default-package>
<bean class="Customer" ignore-annotations="false">
<class ignore-annotations="true">
[...]
</class>
</bean>
<bean class="com.acme.common.model.Address">
<class>
[...]
</class>
</bean>
</constraint-mappings>
9.1.1.2. Field-level overriding
Field level annotations are described via the field
element. The name
attribute corresponds to the name of the field considered. If ignore-annotations
is declared, Bean Validation must honor the explicit value for this element. If not declared, the default value defined in the encapsulating bean
element is considered.
When ignore-annotations
is true, field-level Bean Validation annotations on the targeted field are ignored (including @Valid
and @ConvertGroup
). When ignore-annotations
is false:
-
Constraints declared in XML and constraints declared in annotations are added and form the list of field-level declared constraints.
-
@Valid
is considered unless thevalid
element is explicitly used. Note that the only way to disable cascading on a field marked as@Valid
is to useignore-annotations=true
. -
Group conversions declared in XML and via the
@ConvertGroup
annotation are added and form the list of applied conversions. Note that the rules for the declaration of group conversions as outlined in Group conversion apply, in particular it is not legal to declare several conversions for the same source group.
If the name of the field does not correspond to a field in the given bean a ValidationException
is raised.
<?xml version="1.0" encoding="UTF-8"?>
<constraint-mappings
xmlns="http://xmlns.jcp.org/xml/ns/validation/mapping"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/validation/mapping
http://xmlns.jcp.org/xml/ns/validation/mapping/validation-mapping-2.0.xsd"
version="2.0">
<default-package>com.acme.app.domain</default-package>
<bean class="Customer" ignore-annotations="false">
<field name="firstName">
[...]
</field>
<field name="orders">
<valid/>
[...]
</field>
</bean>
</constraint-mappings>
9.1.1.3. Property-level overriding
Property-level annotations are described via the getter
element. The name
attribute corresponds to the name of the property considered as defined in Field and property validation (for example a getter String getAge()
would have <getter name="age"/>
as a corresponding descriptor). If ignore-annotations
is declared, Bean Validation must honor the explicit value for this element. If not declared, the default value defined in the encapsulating bean
element is considered.
When ignore-annotations
is true, property-level Bean Validation annotations on the targeted property are ignored (including @Valid
and @ConvertGroup
). When ignore-annotations
is false:
-
Constraints declared in XML and constraints declared in annotations are added and form the list of property-level declared constraints.
-
@Valid
is considered unless thevalid
element is explicitly used. Note that the only way to disable cascading on a property marked as@Valid
is to useignore-annotations=true
. -
Group conversions declared in XML and via the
@ConvertGroup
annotation are added and form the list of applied conversions. Note that the rules for the declaration of group conversions as outlined in Group conversion apply, in particular it is not legal to declare several conversions for the same source group.
If the name of the property does not correspond to a property in the given bean a ValidationException
is raised.
<?xml version="1.0" encoding="UTF-8"?>
<constraint-mappings
xmlns="http://xmlns.jcp.org/xml/ns/validation/mapping"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/validation/mapping
http://xmlns.jcp.org/xml/ns/validation/mapping/validation-mapping-2.0.xsd"
version="2.0">
<default-package>com.acme.app.domain</default-package>
<bean class="Customer" ignore-annotations="false">
<getter name="firstName">
[...]
</getter>
<getter name="orders">
<valid/>
[...]
</getter>
</bean>
</constraint-mappings>
9.1.1.4. Constructor-level overriding
Constructor-level annotations are described via the constructor
element.
To identify a constructor to be configured, zero or more parameter
elements are used, matching the number and types of parameters of the configured constructor. When configuring the default constructor, no parameter
element is to be used. The parameter types are specified using their fully qualified name using the syntax described in the documentation of java.lang.Class.getName()
.
Let’s look at some examples:
-
"java.lang.String"
must be specified for a parameter of typejava.lang.String
-
"long"
must be specified for a parameter of typelong
-
"[Ljava.lang.Object;"
must be specified for a parameter of typejava.lang.Object[]
Varargs parameters are specified using the corresponding array type, e.g. a parameter String...
must be specified as "[Ljava.lang.String;"
.
If the default-package
element is configured for the mapping file, any unqualified class names will be resolved using the given default package.
Note
|
You must declare all parameters even if they are not reconfigured to ensure the right constructor is identified. |
If no constructor with the specified parameter types exists in the given bean a ValidationException
is raised.
The optional return-value
element is used to change the configuration of a constructor’s return value if required.
The optional cross-parameter
element is used to change the configuration of a constructor’s cross-parameter constraints if required.
The constraints applying for a constructor’s parameters and its return value are specified by adding constraint
elements to the parameter
and return-value
elements respectively. Whether or not to perform cascaded validation is controlled using the valid
element . Group conversion rules for cascaded validation are specified using the convert-group
element.
The cross-parameter constraints applied on a constructor parameter list are specified by adding constraint
elements to the cross-parameter
element.
If ignore-annotations
is declared on the parameter
, cross-parameter
or return-value
element, Bean Validation must honor the explicit value for this element. Otherwise, if ignore-annotations
is declared for the constructor
element, Bean Validation must honor this value. Otherwise, the default value declared in the encapsulating bean
element is considered.
When ignore-annotations
is true, Bean Validation annotations on the targeted constructor or parameter are ignored (including @Valid
and @ConvertGroup
). When ignore-annotations
is false:
-
Constraints declared in XML and constraints declared in annotations are added and form the list of declared parameter, cross-parameter or return value constraints respectively.
-
@Valid
is considered unless thevalid
element is explicitly used. Note that the only way to disable cascading on a constructor parameter or return value marked as@Valid
is to useignore-annotations=true
. This does not apply to cross-parameter elements as cascading does not make sense in this situation. -
Group conversions declared in XML and via the
@ConvertGroup
annotation are added and form the list of applied conversions. Note that the rules for the declaration of group conversions as outlined in Group conversion apply, in particular it is not legal to declare several conversions for the same source group. This does not apply to cross-parameter elements as cascading does not make sense in this situation.
<?xml version="1.0" encoding="UTF-8"?>
<constraint-mappings
xmlns="http://xmlns.jcp.org/xml/ns/validation/mapping"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/validation/mapping
http://xmlns.jcp.org/xml/ns/validation/mapping/validation-mapping-2.0.xsd"
version="2.0">
<default-package>com.acme.app.domain</default-package>
<bean class="Customer" ignore-annotations="false">
<constructor ignore-annotations="true">
<parameter type="java.lang.String">
[...]
</parameter>
<parameter type="int">
<valid/>
[...]
</parameter>
<parameter type="long" ignore-annotations="false"/>
<cross-parameter ignore-annotations="false">
[...]
</cross-parameter>
<return-value>
<valid/>
[...]
</return-value>
[...]
</constructor>
</bean>
</constraint-mappings>
9.1.1.5. Method-level overriding
Method-level annotations are described via the method
element.
To identify a method to be configured, zero or more parameter
elements are used, matching the number and types of parameters of the configured method. The parameter types are specified using their fully qualified name using the syntax described in the documentation of java.lang.Class.getName()
.
Let’s look at some examples:
-
"java.lang.String"
must be specified for a parameter of typejava.lang.String
-
"long"
must be specified for a parameter of typelong
-
"[Ljava.lang.Object;"
must be specified for a parameter of typejava.lang.Object[]
Varargs parameters are specified using the corresponding array type, e.g. a parameter String...
must be specified as "[Ljava.lang.String;"
.
If the default-package
element is configured for the mapping file, any unqualified class names will be resolved using the given default package.
Note
|
You must declare all parameters even if they are not reconfigured to ensure the right method is identified. |
Note
|
A given getter method representing a JavaBeans property may either be configured using the |
If no method with the specified name and parameter types exists in the given bean a ValidationException
is raised.
The optional return-value
element is used to change the configuration of a method’s return value if required.
The optional cross-parameter
element is used to change the configuration of a method’s cross-parameter constraints if required.
The constraints applying for a method’s parameters and its return value are specified by adding constraint
elements to the parameter
and return-value
elements respectively. Whether or not to perform cascaded validation is controlled using the valid
element. Group conversion rules for cascaded validation are specified using the convert-group
element.
The cross-parameter constraints applied on a method parameter list are specified by adding constraint
elements to the cross-parameter
element.
If ignore-annotations
is declared on the parameter
, cross-parameter
or return-value
element, Bean Validation must honor the explicit value for this element. Otherwise, if ignore-annotations
is declared for the method
element, Bean Validation must honor this value. Otherwise, the default value declared in the encapsulating bean
element is considered.
When ignore-annotations
is true, Bean Validation annotations on the targeted method or parameter are ignored (including @Valid
and @ConvertGroup
). When ignore-annotations
is false:
-
Constraints declared in XML and constraints declared in annotations are added and form the list of declared parameter, cross-parameter or return value constraints respectively.
-
@Valid
is considered unless thevalid
element is explicitly used. Note that the only way to disable cascading on a method parameter or return value marked as@Valid
is to useignore-annotations=true
. This does not apply to cross-parameter elements as cascading does not make sense in this situation. -
Group conversions declared in XML and via the
@ConvertGroup
annotation are added and form the list of applied conversions. Note that the rules for the declaration of group conversions as outlined in Group conversion apply, in particular it is not legal to declare several conversions for the same source group. This does not apply to cross-parameter elements as cascading does not make sense in this situation.
<?xml version="1.0" encoding="UTF-8"?>
<constraint-mappings
xmlns="http://xmlns.jcp.org/xml/ns/validation/mapping"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/validation/mapping
http://xmlns.jcp.org/xml/ns/validation/mapping/validation-mapping-2.0.xsd"
version="2.0">
<default-package>com.acme.app.domain</default-package>
<bean class="Customer" ignore-annotations="false">
<method name="update" ignore-annotations="true">
<parameter type="java.lang.String">
[...]
</parameter>
<parameter type="int">
<valid/>
[...]
</parameter>
<parameter type="long" ignore-annotations="false"/>
<cross-parameter ignore-annotations="false">
[...]
</cross-parameter>
<return-value>
<valid/>
[...]
</return-value>
[...]
</method>
</bean>
</constraint-mappings>
9.1.1.6. Container-element overriding
To apply constraints to the elements of generic container types or to mark them for cascaded validation, the container-element-type
element is used.
container-element-type
can be used within the field
, getter
, parameter
and return-value
elements.
The type-argument-index
is used to specify the index of the configured type argument.
The type-argument-index
can be omitted, if the container type has exactly one type argument.
The ignore-annotations
settings effectively applying to the encapsulating element (field
, getter
etc.) are applied to container-element-type
, too.
The container-element-type
element can be nested for configuring nested generic containers such as List<List<String>>
.
Constraints are applied by adding constraint
elements to container-element-type
.
Whether or not to perform cascaded validation is controlled using the valid
element.
Group conversion rules for cascaded validation are specified using the convert-group
element.
If an invalid container element type configuration is detected, a ValidationException
is raised.
This includes the following configuration errors:
-
The type of the surrounding element (field, getter etc.) has no type arguments.
-
The type of the surrounding element has no type argument with the index given via
type-argument-index
. -
The type of the surrounding element has multiple type arguments and no index is given via
type-argument-index
. -
The same type argument of the surrounding element is configured multiple times.
<?xml version="1.0" encoding="UTF-8"?>
<constraint-mappings
xmlns="http://xmlns.jcp.org/xml/ns/validation/mapping"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/validation/mapping
http://xmlns.jcp.org/xml/ns/validation/mapping/validation-mapping-2.0.xsd"
version="2.0">
<default-package>com.acme.app.domain</default-package>
<bean class="Customer" ignore-annotations="false">
<!-- Map<String, Address> -->
<field name="addressesByType" ignore-annotations="true">
<container-element-type type-argument-index="0">
[...]
</container-element-type>
<container-element-type type-argument-index="1">
<valid/>
[...]
</container-element-type>
[...]
</field>
<!-- setContactsByType(Map<String, List<String>>) -->
<method name="setContactsByType" ignore-annotations="true">
<parameter type="java.util.Map">
<container-element-type type-argument-index="1">
<valid/>
<container-element-type type-argument-index="0">
<valid/>
[...]
</container-element-type>
[...]
</container-element-type>
[...]
</parameter>
[...]
</method>
</bean>
</constraint-mappings>
9.1.1.7. Constraint declaration
New constraint declarations are represented by the constraint
element. The annotation
attribute is the class name of the annotation representing the constraint. Message, groups and payload are defined respectively by the message
, groups
and payload
elements.
Other custom elements of an annotation are represented by element
. The name
attribute is mandatory and represents the name of the element in the constraint declaration. message
, groups
and payload
are not permitted names, use the message
, groups
or payload
elements instead. Otherwise a ValidationException
is raised.
Note
|
|
If the element represents a primitive type, a class or an enum, the string representation of its value is placed in the element itself. See Converting the string representation of a value for a detailed explanation of the conversion rules from string to the type.
If the element represents a primitive type array, a class array or an enum array, the string representation of each value is placed in a value
element placed under the element itself.
If the element represents an annotation, the annotation
element is used to represent the annotation and placed under element
. An annotation
element contains element
elements.
If the element represents an array of annotations, one or more annotation
elements are placed under element
.
Elements with default values in the annotation definition do not have to be represented in XML: the default value will be used in this case. If an XML constraint declaration is missing mandatory elements, or if it contains elements not part of the constraint definition, a ValidationException
is raised.
<?xml version="1.0" encoding="UTF-8"?>
<constraint-mappings
xmlns="http://xmlns.jcp.org/xml/ns/validation/mapping"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/validation/mapping
http://xmlns.jcp.org/xml/ns/validation/mapping/validation-mapping-2.0.xsd"
version="2.0">
<default-package>com.acme.app.domain</default-package>
<bean class="Customer" ignore-annotations="false">
<field name="firstName">
<!-- @LooksLike(patterns={
@Pattern(value="myRegExp", flag=PatternFlag.INSENSITIVE),
@Pattern(value="my2ndRegExp")}
)
-->
<constraint annotation="com.acme.app.constraint.LooksLike">
<element name="patterns">
<annotation>
<element name="value">myRegExp</element>
<element name="flag">
<value>INSENSITIVE</value>
</element>
</annotation>
<annotation>
<element name="value">my2ndRegExp</element>
</annotation>
</element>
</constraint>
</field>
<field name="orders">
<valid/>
<!-- @DiscreteSize(value={ 0, 20 } )
-->
<constraint annotation="com.acme.app.constraint.DiscreteSize">
<element name="value">
<value>0</value>
<value>20</value>
</element>
</constraint>
</field>
<!-- Map<@NotBlank String, @Valid PhoneNumber>
-->
<field name="phoneNumbersByType">
<container-element-type type-argument-index="0">
<constraint annotation="javax.validation.constraints.NotBlank"/>
</container-element-type>
<container-element-type type-argument-index="1">
<valid/>
</container-element-type>
</field>
<getter name="orders">
<valid/>
<!-- @Size(message="Size is limited",
groups={Default.class, LightValidation.class},
max=30
)
-->
<constraint annotation="javax.validation.constraints.Size">
<message>Size is limited</message>
<groups>
<value>com.acme.app.model.LightValidation</value>
<value>javax.persistence.Default</value>
</groups>
<payload>
<value>com.acme.app.model.WARN</value>
</payload>
<element name="max">30</element>
</constraint>
</getter>
<constructor ignore-annotations="true">
<parameter type="java.lang.String">
<!-- @DiscreteSize(value={ 0, 20 } ) -->
<constraint annotation="com.acme.app.constraint.DiscreteSize">
<element name="value">
<value>0</value>
<value>20</value>
</element>
</constraint>
</parameter>
</constructor>
<method name="update" ignore-annotations="true">
<parameter type="java.lang.String">
<!-- @DiscreteSize(value={ 0, 20 } ) -->
<constraint annotation="com.acme.app.constraint.DiscreteSize">
<element name="value">
<value>0</value>
<value>20</value>
</element>
</constraint>
</parameter>
<return-value>
<!-- @ValidCustomer -->
<constraint annotation="com.acme.app.constraint.ValidCustomer"/>
</return-value>
</method>
<method name="resetPassword" ignore-annotations="false">
<parameter type="java.lang.String"/>
<parameter type="java.lang.String"/>
<cross-parameter>
<!-- @ValidResetPasswordParameters -->
<constraint
annotation="com.acme.app.constraint.ValidResetPasswordParameters"/>
</cross-parameter>
</method>
</bean>
</constraint-mappings>
9.1.1.8. Declaration of group conversions
Group conversion rules are declared by specifying one or more convert-group
elements within the field
, getter
, parameter
, return-value
and container-element-type
elements.
Source and target group of a conversion rule are given by specifying their fully-qualified names within the from
and to
attribute respectively. If the default-package
element is configured for the mapping file, any unqualified class names will be resolved using the given default package.
<?xml version="1.0" encoding="UTF-8"?>
<constraint-mappings
xmlns="http://xmlns.jcp.org/xml/ns/validation/mapping"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/validation/mapping
http://xmlns.jcp.org/xml/ns/validation/mapping/validation-mapping-2.0.xsd"
version="2.0">
<default-package>com.acme.app.domain</default-package>
<bean class="Customer" ignore-annotations="false">
<field name="firstName">
<valid/>
<convert-group from="javax.validation.groups.Default"
to="com.acme.CustomerBasic"/>
<convert-group from="com.acmenote.Advanced" to="com.acme.CustomerComplex"/>
</field>
<getter name="orders">
<valid/>
<convert-group from="javax.validation.groups.Default"
to="com.acme.CustomerBasic"/>
</getter>
<constructor>
<parameter type="java.lang.String">
<valid/>
<convert-group from="javax.validation.groups.Default"
to="com.acme.CustomerBasic"/>
</parameter>
<return-value>
<valid/>
<convert-group from="javax.validation.groups.Default"
to="com.acme.CustomerBasic"/>
</return-value>
</constructor>
<method name="update">
<parameter type="java.lang.String">
<valid/>
<convert-group from="javax.validation.groups.Default"
to="com.acme.CustomerBasic"/>
</parameter>
<return-value>
<valid/>
<convert-group from="javax.validation.groups.Default"
to="com.acme.CustomerBasic"/>
</return-value>
</constructor>
</bean>
</constraint-mappings>
9.1.2. Overriding constraint definitions in XML
A constraint definition (i.e. the annotation representing a constraint), cannot be fully expressed in XML but the list of ConstraintValidator
s associated to a given constraint can be altered.
A constraint definition is represented by a constraint-definition
element. The annotation
attribute represents the constraint annotation being altered. The validated-by
elements represent the (ordered) list of ConstraintValidator
implementations associated to the constraint.
If include-existing-validator
is set to false, ConstraintValidator
defined on the constraint annotation are ignored. If set to true, the list of ConstraintValidator
s described in XML are concatenated to the list of ConstraintValidator
described on the annotation to form a new array of ConstraintValidator
evaluated. Annotation based ConstraintValidator
s come before XML based ConstraintValidator
s in the array. The new list is returned by ConstraintDescriptor.getConstraintValidatorClasses()
.
<?xml version="1.0" encoding="UTF-8"?>
<constraint-mappings
xmlns="http://xmlns.jcp.org/xml/ns/validation/mapping"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/validation/mapping
http://xmlns.jcp.org/xml/ns/validation/mapping/validation-mapping-2.0.xsd"
version="2.0">
<default-package>com.acme.app.domain</default-package>
<bean class="com.acme.common.model.Address">
[...]
</bean>
<constraint-definition annotation="javax.validation.constraints.Size">
<validated-by include-existing-validators="true">
<value>com.acme.app.constraint.SizeValidatorForDictionary</value>
</validated-by>
</constraint-definition>
<constraint-definition annotation="AcmeOrderNumber">
[...]
</constraint-definition>
</constraint-mappings>
9.1.3. Converting the string representation of a value
Primitive types, Class
and Enum
are represented as strings in the XML descriptor. Elements of an array are represented by the value
element.
A byte
is represented according to the rules defined in Byte.parseByte(String)
.
A short
is represented according to the rules defined in Short.parseShort(String)
.
An int
is represented according to the rules defined in Integer.parseInt(String)
.
A long
is represented according to the rules defined in Long.parseLong(String)
.
A float
is represented according to the rules defined in Float.parseFloat(String)
.
A double
is represented according to the rules defined in Double.parseDouble(String)
.
A boolean
is represented according to the rules defined in Boolean.parseBoolean(String)
.
A char
is represented according to the following rules:
-
the string must be of one character long
-
the character extracted from the string is the returned
char
A Class
is represented by the fully qualified class name of the class or more precisely according to the syntax described in the documentation of java.lang.Class.getName()
. Note that if the raw string is unqualified, default package is taken into account.
An enum is represented by its enum.name()
value.
If any of the string representation does not match its type counterpart, a ValidationException
is raised.
9.1.4. XML Schema
This section contains the XML schema used for constraint mapping descriptors.
From Bean Validation revision 1.1 onwards, mapping authors must specify the used version of the schema within the version
attribute of the constraint-mappings
element. Implementations supporting Bean Validation 2.0 must properly parse mapping descriptors of Bean Validation 1.0, 1.1 and 2.0. If the version
attribute attribute is not given, schema version 1.0 is to be assumed by the Bean Validation provider.
In case an unknown version is given (e.g. if a mapping descriptor adhering to a future schema version is parsed by a Bean Validation 2.0 provider) a ValidationException
is raised.
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema attributeFormDefault="unqualified"
elementFormDefault="qualified"
targetNamespace="http://xmlns.jcp.org/xml/ns/validation/mapping"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:map="http://xmlns.jcp.org/xml/ns/validation/mapping"
version="2.0">
<xs:annotation>
<xs:documentation><![CDATA[
This is the XML Schema for Bean Validation constraint mapping files.
Bean Validation constraint mapping files must indicate the Bean Validation
XML schema by using the constraint mapping namespace:
http://xmlns.jcp.org/xml/ns/validation/mapping
and indicate the version of the schema by using the version attribute
as shown below:
<constraint-mappings
xmlns="http://xmlns.jcp.org/xml/ns/validation/mapping"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://xmlns.jcp.org/xml/ns/validation/mapping
http://xmlns.jcp.org/xml/ns/validation/mapping/validation-mapping-2.0.xsd"
version="2.0">
...
</constraint-mappings>
]]>
</xs:documentation>
</xs:annotation>
<xs:element name="constraint-mappings" type="map:constraint-mappingsType"/>
<xs:complexType name="payloadType">
<xs:sequence>
<xs:element type="xs:string" name="value" maxOccurs="unbounded" minOccurs="0"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="groupsType">
<xs:sequence>
<xs:element type="xs:string" name="value" maxOccurs="unbounded" minOccurs="0"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="groupSequenceType">
<xs:sequence>
<xs:element type="xs:string" name="value" maxOccurs="unbounded" minOccurs="0"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="groupConversionType">
<xs:attribute type="xs:string" name="from" use="optional"/>
<xs:attribute type="xs:string" name="to" use="required"/>
</xs:complexType>
<xs:complexType name="constraint-mappingsType">
<xs:sequence>
<xs:element type="xs:string" name="default-package" minOccurs="0"/>
<xs:element type="map:beanType"
name="bean"
maxOccurs="unbounded"
minOccurs="0"/>
<xs:element type="map:constraint-definitionType