Hibernate.orgCommunity Documentation
In this chapter you will learn how to make use of several features provided by Hibernate Validator in addition to the functionality defined by the Bean Validation specification. This includes the fail fast mode, the API for programmatic constraint configuration and the boolean composition of constraints.
Using the features described in the following sections may result in application code which is not portable between Bean Validation providers.
Let's start, however, with a look at the public API of Hibernate Validator. Table 11.1, “Hibernate Validator public API” lists all packages belonging to this API and describes their purpose. Note that when a package is part of the public this is not necessarily true for its sub-packages.
Table 11.1. Hibernate Validator public API
| Packages | Description |
|---|---|
| org.hibernate.validator | Classes used by the Bean Validation bootstrap mechanism (eg. validation provider, configuration class); For more details see Chapter 8, Bootstrapping. |
| org.hibernate.validator.cfg, org.hibernate.validator.cfg.context, org.hibernate.validator.cfg.defs | Hibernate Validator's fluent API for constraint
declaration; In org.hibernate.validator.cfg you
will find the ConstraintMapping interface
and in org.hibernate.validator.cfg.defs all
constraint definitions. Refer to Section 11.3, “Programmatic constraint declaration” for the details. |
| org.hibernate.validator.constraints, org.hibernate.validator.constraints.br | Some useful custom constraints provided by Hibernate Validator in addition to the built-in constraints defined by the Bean Validation specification; The constraints are described in detail in Section 2.3.2, “Additional constraints”. |
| org.hibernate.validator.constraintvalidation | Extended constraint validator context which allows to set custom attributes for message interpolation. Section 11.6.1, “HibernateConstraintValidatorContext” describes how to make use of that feature. |
| org.hibernate.validator.group, org.hibernate.validator.spi.group | The group sequence provider feature which allows you to define dynamic default group sequences in function of the validated object state; The specifics can be found in Section 5.3, “Redefining the default group sequence”. |
| org.hibernate.validator.messageinterpolation, org.hibernate.validator.resourceloading, org.hibernate.validator.spi.resourceloading | Classes related to constraint message interpolation; The
first package contains Hibernate Validator's default message
interpolator,
ResourceBundleMessageInterpolator. The
latter two packages provide the
ResourceBundleLocator SPI for the loading of resource
bundles (see Section 4.2.1, “ResourceBundleLocator”)
and its default implementation. |
| org.hibernate.validator.parameternameprovider | A ParameterNameProvider based on the
ParaNamer library, see Section 11.7, “ParaNamer based
ParameterNameProvider”. |
| org.hibernate.validator.valuehandling, org.hibernate.validator.spi.valuehandling | Classes related to the processing of values prior to their validation, see Section 11.8, “Unwrapping values prior to validation”. |
The public packages of Hibernate Validator fall into two
categories: while the actual API parts are intended to be
invoked or used by clients
(e.g. the API for programmatic constraint declaration or the custom
constraints), the SPI (service provider interface) packages contain
interfaces which are intended to be implemented by
clients (e.g. ResourceBundleLocator).
Any packages not listed in that table are internal packages of Hibernate Validator and are not intended to be accessed by clients. The contents of these internal packages can change from release to release without notice, thus possibly breaking any client code relying on it.
Using the fail fast mode, Hibernate Validator allows to return from the current validation as soon as the first constraint violation occurs. This can be useful for the validation of large object graphs where you are only interested in a quick check whether there is any constraint violation at all.
Example 11.1, “Using the fail fast validation mode” shows how to bootstrap and use a fail fast enabled validator.
Example 11.1. Using the fail fast validation mode
package org.hibernate.validator.referenceguide.chapter11.failfast;
public class Car {
@NotNull
private String manufacturer;
@AssertTrue
private boolean isRegistered;
public Car(String manufacturer, boolean isRegistered) {
this.manufacturer = manufacturer;
this.isRegistered = isRegistered;
}
//getters and setters...
}
Validator validator = Validation.byProvider( HibernateValidator.class )
.configure()
.failFast( true )
.buildValidatorFactory()
.getValidator();
Car car = new Car( null, false );
Set<ConstraintViolation<Car>> constraintViolations = validator.validate( car );
assertEquals( 1, constraintViolations.size() );
Here the validated object actually fails to satisfy both the
constraints declared on the Car class, yet the
validation call yields only one ConstraintViolation
since the fail fast mode is enabled.
There is no guarantee in which order the constraints are
evaluated, i.e. it is not deterministic whether the returned violation
originates from the @NotNull or the
@AssertTrue constraint. If required, a
deterministic evaluation order can be enforced using group sequences as
described in Section 5.2, “Defining group sequences”.
Refer to Section 8.2.6, “Provider-specific settings” to learn about the different ways of enabling the fail fast mode when bootstrapping a validator.
As per the Bean Validation specification, you can declare constraints using Java annotations and XML based constraint mappings.
In addition, Hibernate Validator provides a fluent API which allows for the programmatic configuration of constraints. Use cases include the dynamic addition of constraints at runtime depending on some application state or tests where you need entities with different constraints in different scenarios but don't want to implement actual Java classes for each test case.
By default, constraints added via the fluent API are additive to constraints configured via the standard configuration capabilities. But it is also possible to ignore annotation and XML configured constraints where required.
The API is centered around the
ConstraintMapping interface. You obtain a new
mapping via
HibernateValidatorConfiguration#createConstraintMapping()
which you then can configure in a fluent manner as shown in Example 11.2, “Programmatic constraint declaration”.
Example 11.2. Programmatic constraint declaration
HibernateValidatorConfiguration configuration = Validation
.byProvider( HibernateValidator.class )
.configure();
ConstraintMapping constraintMapping = configuration.createConstraintMapping();
constraintMapping
.type( Car.class )
.property( "manufacturer", FIELD )
.constraint( new NotNullDef() )
.property( "licensePlate", FIELD )
.ignoreAnnotations()
.constraint( new NotNullDef() )
.constraint( new SizeDef().min( 2 ).max( 14 ) )
.type( RentalCar.class )
.property( "rentalStation", METHOD )
.constraint( new NotNullDef() );
Validator validator = configuration.addMapping( constraintMapping )
.buildValidatorFactory()
.getValidator();
Constraints can be configured on multiple classes and properties
using method chaining. The constraint definition classes
NotNullDef and SizeDef are
helper classes which allow to configure constraint parameters in a
type-safe fashion. Definition classes exist for all built-in constraints
in the org.hibernate.validator.cfg.defs package. By
calling ignoreAnnotations() any constraints
configured via annotations or XML are ignored for the given
element.
Each element (type, property, method etc.) may only be configured
once within all the constraint mappings used to set up one validator
factory. Otherwise a ValidationException is
raised.
It is not supported to add constraints to non-overridden supertype properties and methods by configuring a subtype. Instead you need to configure the supertype in this case.
Having configured the mapping, you must add it back to the configuration object from which you then can obtain a validator factory.
For custom constraints you can either create your own definition
classes extending ConstraintDef or you can use
GenericConstraintDef as seen in Example 11.3, “Programmatic declaration of a custom constraint”.
Example 11.3. Programmatic declaration of a custom constraint
ConstraintMapping constraintMapping = configuration.createConstraintMapping();
constraintMapping
.type( Car.class )
.property( "licensePlate", FIELD )
.constraint( new GenericConstraintDef<CheckCase>( CheckCase.class )
.param( "value", CaseMode.UPPER )
);
By invoking valid() you can mark a member
for cascaded validation which is equivalent to annotating it with
@Valid. Configure any group conversions to be
applied during cascaded validation using the
convertGroup() method (equivalent to
@ConvertGroup). An example can be seen in Example 11.4, “Marking a property for cascaded validation”.
Example 11.4. Marking a property for cascaded validation
ConstraintMapping constraintMapping = configuration.createConstraintMapping();
constraintMapping
.type( Car.class )
.property( "driver", FIELD )
.constraint( new NotNullDef() )
.valid()
.convertGroup( Default.class ).to( PersonDefault.class )
.type( Person.class )
.property( "name", FIELD )
.constraint( new NotNullDef().groups( PersonDefault.class ) );
You can not only configure bean constraints using the fluent API but also method and constructor constraints. As shown in Example 11.5, “Programmatic declaration of method and constructor constraints” constructors are identified by their parameter types and methods by their name and parameter types. Having selected a method or constructor, you can mark its parameters and/or return value for cascaded validation and add constraints as well as cross-parameter constraints.
Example 11.5. Programmatic declaration of method and constructor constraints
ConstraintMapping constraintMapping = configuration.createConstraintMapping();
constraintMapping
.type( Car.class )
.constructor( String.class )
.parameter( 0 )
.constraint( new SizeDef().min( 3 ).max( 50 ) )
.returnValue()
.valid()
.method( "drive", int.class )
.parameter( 0 )
.constraint( new MaxDef().value ( 75 ) )
.method( "load", List.class, List.class )
.crossParameter()
.constraint( new GenericConstraintDef<LuggageCountMatchesPassengerCount>(
LuggageCountMatchesPassengerCount.class ).param(
"piecesOfLuggagePerPassenger", 2
)
)
.method( "getDriver" )
.returnValue()
.constraint( new NotNullDef() )
.valid();
Last but not least you can configure the default group sequence or the default group sequence provider of a type as shown in the following example.
Example 11.6. Configuration of default group sequence and default group sequence provider
ConstraintMapping constraintMapping = configuration.createConstraintMapping();
constraintMapping
.type( Car.class )
.defaultGroupSequence( Car.class, CarChecks.class )
.type( RentalCar.class )
.defaultGroupSequenceProviderClass( RentalCarGroupSequenceProvider.class );
Bean Validation specifies that the constraints of a composed
constraint (see Section 6.4, “Constraint composition”) are all
combined via a logical AND. This means all of the
composing constraints need to return true in order
for an overall successful validation.
Hibernate Validator offers an extension to this and allows you to
compose constraints via a logical OR or
NOT. To do so you have to use the
ConstraintComposition annotation and the enum
CompositionType with its values
AND, OR and
ALL_FALSE.
Example 11.7, “OR composition of constraints” shows how
to build a composed constraint @PatternOrSize where
only one of the composing constraints needs to be valid in order to pass
the validation. Either the validated string is all lower-cased or it is
between two and three characters long.
Example 11.7. OR composition of constraints
package org.hibernate.validator.referenceguide.chapter11.booleancomposition;
@ConstraintComposition(OR)
@Pattern(regexp = "[a-z]")
@Size(min = 2, max = 3)
@ReportAsSingleViolation
@Target({ METHOD, FIELD })
@Retention(RUNTIME)
@Constraint(validatedBy = { })
public @interface PatternOrSize {
String message() default "{org.hibernate.validator.referenceguide.chapter11." +
"booleancomposition.PatternOrSize.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
}
Using ALL_FALSE as composition type implicitly enforces that only a single violation will get reported in case validation of the constraint composition fails.
As described in Section 4.2, “Custom message interpolation”, Bean Validation allows to plug in custom message interpolator implementations.
With ResourceBundleLocator, Hibernate
Validator provides an additional SPI which allows to retrieve error
messages from other resource bundles than
ValidationMessages while still using the actual
interpolation algorithm as defined by the specification. Refer to Section 4.2.1, “ResourceBundleLocator” to learn how to make use of
that SPI.
The Bean Validation specification offers at several points in its
API the possibility to unwrap a given interface to a implementor specific
subtype. In the case of constraint violation creation in
ConstraintValidator implementations as well as
message interpolation in Messageinterpolator
instances, there exist unwrap() methods for the
provided context instances -
ConstraintValidatorContext respectively
MessageInterpolatorContext. Hibernate Validator
provides custom extensions for both of these interfaces.
HibernateConstraintValidatorContext
is a subtype of ConstraintValidatorContext which
allows you to set arbitrary parameters for interpolation via the
Expression Language message interpolation facility (see Section 4.1.2, “Interpolation with message expressions”). For example
the default error message for the @Future
constraint is "must be in the future". What if you would like to include
the current date to make the message more explicit? Example 11.8, “Custom @Future validator with message
parameters” shows how this could be
achieved.
Example 11.8. Custom @Future validator with message
parameters
public class MyFutureValidator implements ConstraintValidator<Future, Date> {
public void initialize(Future constraintAnnotation) {
}
public boolean isValid(Date value, ConstraintValidatorContext context) {
Date now = GregorianCalendar.getInstance().getTime();
if ( value.before( now ) ) {
HibernateConstraintValidatorContext hibernateContext =
context.unwrap( HibernateConstraintValidatorContext.class );
hibernateContext.disableDefaultConstraintViolation();
hibernateContext.addExpressionVariable( "now", now )
.buildConstraintViolationWithTemplate( "Must be after ${now}" )
.addConstraintViolation();
return false;
}
return true;
}
}
Note that the parameters specified via
addExpressionVariable(String, Object) are
global and apply for all constraint violations created by this
isValid() invocation. This includes the
default constraint violation, but also all violations created by the
ConstraintViolationBuilder. You can, however,
update the parameters between invocations of
ConstraintViolationBuilder#addConstraintViolation().
This functionality is currently experimental and might change in future versions.
Hibernate Validator also offers a custom extension of
MessageInterpolatorContext, namely
HibernateMessageInterpolatorContext (see Example 11.9, “HibernateMessageInterpolatorContext”). This subtype
was introduced to allow a better integration of Hibernate Validator into
the Glassfish. The root bean type was in this case needed to determine
the right classloader for the message resource bundle. If you have any
other usecases, let us know.
Example 11.9. HibernateMessageInterpolatorContext
public interface HibernateMessageInterpolatorContext extends MessageInterpolator.Context {
/**
* Returns the currently validated root bean type.
*
* @return The currently validated root bean type.
*/
Class<?> getRootBeanType();
}
Hibernate Validator comes with a
ParameterNameProvider implementation which
leverages the ParaNamer library.
This library provides several ways for obtaining parameter names at
runtime, e.g. based on debug symbols created by the Java compiler,
constants with the parameter names woven into the bytecode in a
post-compile step or annotations such as the @Named
annotation from JSR 330.
In order to use
ParanamerParameterNameProvider, either pass an
instance when bootstrapping a validator as shown in Example 8.8, “Using a custom
ParameterNameProvider” or specify
org.hibernate.validator.parameternameprovider.ParanamerParameterNameProvider
as value for the <parameter-name-provider>
element in the META-INF/validation.xml file.
When using this parameter name provider, you need to add the
ParaNamer library to your classpath. It is available in the Maven
Central repository with the group id
com.thoughtworks.paranamer and the artifact id
paranamer.
By default ParanamerParameterNameProvider
retrieves parameter names from constants added to the byte code at build
time (via DefaultParanamer) and debug symbols (via
BytecodeReadingParanamer). Alternatively you can
specify a Paranamer implementation of your choice
when creating a ParanamerParameterNameProvider
instance.
Sometimes it is required to unwrap values prior to the validation. E.g. in Example 11.10, “Using@UnwrapValidatedValue” property types as specified by JavaFX are used to define an element of some domain model.
Example 11.10. Using@UnwrapValidatedValue
@Size(min = 3)
@UnwrapValidatedValue
private Property<String> name = new SimpleStringProperty( "Bob" );
The concept of value unwrapping is considered experimental at this time and may evolve into more general means of value handling in future releases. Please let us know about your use cases for such functionality.
In JavaFX, bean properties are typically not of simple data types
like String or int, but are
wrapped in Property types which allows to make them
observable, use them for data binding etc. When applying a constraint such
as @Size to an element of type
Property<String> without further preparation,
an exception would be raised, indicating that no suitable validator for
that constraint and data type can be found. Thus the validated value must
be unwrapped from the containing property object before looking up a
validator and invoking it.
To do so, put the @UnwrapValidatedValue
annotation to the element in question. This will advice the validation
engine to look for an unwrapper implementation which returns the data type
to be used for constraint validator resolution and unwraps the validated
value. Unwrapper types must extend the SPI class
ValidatedValueUnwrapper as shown in
Example 11.11, “Implementing the ValidatedValueUnwrapper
interface”.
Example 11.11. Implementing the ValidatedValueUnwrapper
interface
public class PropertyValueUnwrapper extends ValidatedValueUnwrapper<Property<?>> {
@Override
public Object handleValidatedValue(Property<?> value) {
//...
}
@Override
public Type getValidatedValueType(Type valueType) {
//...
}
}
Value unwrappers must be registered when obtaining a Validator
instance as follows:
Example 11.12. Registering a ValidatedValueUnwrapper
Validator validator = Validation.byProvider( HibernateValidator.class )
.configure()
.addValidatedValueHandler( new PropertyValueUnwrapper() )
.buildValidatorFactory()
.getValidator();
Several unwrapper implementations can be registered when working with different kinds of wrapper types in one application. Note that it is not specified which of the unwrapper implementations is chosen when more than one implementation is suitable to unwrap a given element.
Alternatively, the fully-qualified names of one ore more unwrapper
implementations can be specified via the configuration property
hibernate.validator.validated_value_handlers which
can be useful when configuring the default validator factory using the
descriptor META-INF/validation.xml (see Chapter 7, Configuring via XML).
Copyright © 2009 - 2013 Red Hat, Inc. & Gunnar Morling