Chapter 10. Integrating with other frameworks

Hibernate Validator is intended to be used to implement multi-layered data validation, where constraints are expressed in a single place (the annotated domain model) and checked in various different layers of the application. For this reason there are multiple integration points with other technologies.

10.1. ORM integration

Hibernate Validator integrates with both Hibernate and all pure Java Persistence providers.

Tip

When lazy loaded associations are supposed to be validated it is recommended to place the constraint on the getter of the association. Hibernate replaces lazy loaded associations with proxy instances which get initialized/loaded when requested via the getter. If, in such a case, the constraint is placed on field level the actual proxy instance is used which will lead to validation errors.

10.1.1. Database schema-level validation

Out of the box, Hibernate (as of version 3.5.x) will translate the constraints you have defined for your entities into mapping metadata. For example, if a property of your entity is annotated @NotNull, its columns will be declared as not null in the DDL schema generated by Hibernate.

If, for some reason, the feature needs to be disabled, set hibernate.validator.apply_to_ddl to false. See also Table 2.2, “Bean Validation constraints” and Table 2.3, “Custom constraints”.

You can also limit the DDL constraint generation to a subset of the defined constraints by setting the property org.hibernate.validator.group.ddl. The property specifies the comma-separated, fully specified class names of the groups a constraint has to be part of in order to be considered for DDL schema generation.

10.1.2. Hibernate event-based validation

Hibernate Validator has a built-in Hibernate event listener - org.hibernate.cfg.beanvalidation.BeanValidationEventListener - which is part of Hibernate ORM. Whenever a PreInsertEvent, PreUpdateEvent or PreDeleteEvent occurs, the listener will verify all constraints of the entity instance and throw an exception if any constraint is violated. Per default objects will be checked before any inserts or updates are made by Hibernate. Pre deletion events will per default not trigger a validation. You can configure the groups to be validated per event type using the properties javax.persistence.validation.group.pre-persist, javax.persistence.validation.group.pre-update and javax.persistence.validation.group.pre-remove. The values of these properties are the comma-separated, fully specified class names of the groups to validate. Example 10.1, “Manual configuration of BeanValidationEvenListener” shows the default values for these properties. In this case they could also be omitted.

On constraint violation, the event will raise a runtime ConstraintViolationException which contains a set of ConstraintViolation instances describing each failure.

If Hibernate Validator is present in the classpath, Hibernate ORM will use it transparently. To avoid validation even though Hibernate Validator is in the classpath set javax.persistence.validation.mode to none.

Note

If the beans are not annotated with validation annotations, there is no runtime performance cost.

In case you need to manually set the event listeners for Hibernate ORM, use the following configuration in hibernate.cfg.xml:

Example 10.1. Manual configuration of BeanValidationEvenListener

<hibernate-configuration>
    <session-factory>
        ...
        <property name="javax.persistence.validation.group.pre-persist">
            javax.validation.groups.Default
        </property>
        <property name="javax.persistence.validation.group.pre-update">
            javax.validation.groups.Default
        </property>
        <property name="javax.persistence.validation.group.pre-remove"></property>
        ...
        <event type="pre-update">
            <listener class="org.hibernate.cfg.beanvalidation.BeanValidationEventListener"/>
        </event>
        <event type="pre-insert">
            <listener class="org.hibernate.cfg.beanvalidation.BeanValidationEventListener"/>
        </event>
        <event type="pre-delete">
            <listener class="org.hibernate.cfg.beanvalidation.BeanValidationEventListener"/>
        </event>
    </session-factory>
</hibernate-configuration>

10.1.3. JPA

If you are using JPA 2 and Hibernate Validator is in the classpath the JPA2 specification requires that Bean Validation gets enabled. The properties javax.persistence.validation.group.pre-persist, javax.persistence.validation.group.pre-update and javax.persistence.validation.group.pre-remove as described in Section 10.1.2, “Hibernate event-based validation” can in this case be configured in persistence.xml. persistence.xml also defines a node validation-mode which can be set to AUTO, CALLBACK, NONE. The default is AUTO.

In a JPA 1 you will have to create and register Hibernate Validator yourself. In case you are using Hibernate EntityManager you can add a customized version of the BeanValidationEventListener described in Section 10.1.2, “Hibernate event-based validation” to your project and register it manually.

10.2. JSF & Seam

When working with JSF2 or JBoss Seam and Hibernate Validator (Bean Validation) is present in the runtime environment, validation is triggered for every field in the application. Example 10.2, “Usage of Bean Validation within JSF2” shows an example of the f:validateBean tag in a JSF page. The validationGroups attribute is optional and can be used to specify a comma separated list of validation groups. The default is javax.validation.groups.Default. For more information refer to the Seam documentation or the JSF 2 specification.

Example 10.2. Usage of Bean Validation within JSF2

<h:form>

  <f:validateBean validationGroups="javax.validation.groups.Default">

    <h:inputText value=#{model.property}/>
    <h:selectOneRadio value=#{model.radioProperty}> ... </h:selectOneRadio>
    <!-- other input components here -->

  </f:validateBean>

</h:form>

Tip

The integration between JSF 2 and Bean Validation is described in the "Bean Validation Integration" chapter of JSR-314. It is interesting to know that JSF 2 implements a custom MessageInterpolator to ensure ensure proper localization. To encourage the use of the Bean Validation message facility, JSF 2 will per default only display the generated Bean Validation message. This can, however, be configured via the application resource bundle by providing the following configuration ({0} is replaced with the Bean Validation message and {1} is replaced with the JSF component label):

javax.faces.validator.BeanValidator.MESSAGE={1}: {0}

The default is:

javax.faces.validator.BeanValidator.MESSAGE={0}

10.3. CDI

As of version 1.1, Bean Validation is integrated with CDI (Contexts and Dependency Injection for Java^TM EE).

This integration provides CDI managed beans for Validator and ValidatorFactory and enables dependency injection in constraint validators as well as custom message interpolators, traversable resolvers, constraint validator factories and parameter name providers.

Furthermore, parameter and return value constraints on the methods and constructors of CDI managed beans will automatically be validated upon invocation.

When your application runs on a Jave EE container, this integration is enabled by default. When working with CDI in a Servlet container or in a pure Java SE environment, you can use the CDI portable extension provided by Hibernate Validator. To do so, add the portable extension to your class path as described in Section 1.1.2, “CDI”.

10.3.1. Dependency injection

CDI’s dependency injection mechanism makes it very easy to retrieve ValidatorFactory and Validator instances and use them in your managed beans. Just annotate instance fields of your bean with @javax.inject.Inject as shown in Example 10.3, “Retrieving validator factory and validator via @Inject”.

Example 10.3. Retrieving validator factory and validator via @Inject

package org.hibernate.validator.referenceguide.chapter10.cdi.validator;

@ApplicationScoped
public class RentalStation {

	@Inject
	private ValidatorFactory validatorFactory;

	@Inject
	private Validator validator;

	//...
}

The injected beans are the default validator factory and validator instances. In order to configure them - e.g. to use a custom message interpolator - you can use the Bean Validation XML descriptors as discussed in Chapter 7, Configuring via XML.

If you are working with several Bean Validation providers you can make sure that factory and validator from Hibernate Validator are injected by annotating the injection points with the @HibernateValidator qualifier which is demonstrated in Example 10.4, “Using the @HibernateValidator qualifier annotation”.

Example 10.4. Using the @HibernateValidator qualifier annotation

package org.hibernate.validator.referenceguide.chapter10.cdi.validator.qualifier;

@ApplicationScoped
public class RentalStation {

	@Inject
	@HibernateValidator
	private ValidatorFactory validatorFactory;

	@Inject
	@HibernateValidator
	private Validator validator;

	//...
}

Tip

The fully-qualified name of the qualifier annotation is org.hibernate.validator.cdi.HibernateValidator. Be sure to not import org.hibernate.validator.HibernateValidator instead which is the ValidationProvider implementation used for selecting Hibernate Validator when working with the bootstrapping API (see Section 8.1, “Retrieving ValidatorFactory and Validator”).

Via @Inject you also can inject dependencies into constraint validators and other Bean Validation objects such as MessageInterpolator implementations etc.

Example 10.5, “Constraint validator with injected bean” demonstrates how an injected CDI bean is used in a ConstraintValidator implementation to determine whether the given constraint is valid or not. As the example shows, you also can work with the @PostConstruct and @PreDestroy callbacks to implement any required construction and destruction logic.

Example 10.5. Constraint validator with injected bean

package org.hibernate.validator.referenceguide.chapter10.cdi.injection;

public class ValidLicensePlateValidator
		implements ConstraintValidator<ValidLicensePlate, String> {

	@Inject
	private VehicleRegistry vehicleRegistry;

	@PostConstruct
	public void postConstruct() {
		//do initialization logic...
	}

	@PreDestroy
	public void preDestroy() {
		//do destruction logic...
	}

	@Override
	public void initialize(ValidLicensePlate constraintAnnotation) {
	}

	@Override
	public boolean isValid(String licensePlate, ConstraintValidatorContext constraintContext) {
		return vehicleRegistry.isValidLicensePlate( licensePlate );
	}
}

10.3.2. Method validation

The method interception facilities of CDI allow for a very tight integration with Bean Validation’s method validation functionality. Just put constraint annotations to the parameters and return values of the executables of your CDI beans and they will be validated automatically before (parameter constraints) and after (return value constraints) a method or constructor is invoked.

Note that no explicit interceptor binding is required, instead the required method validation interceptor will automatically be registered for all managed beans with constrained methods and constructors.

Note

The interceptor org.hibernate.validator.internal.cdi.interceptor.ValidationInterceptor is registered by org.hibernate.validator.internal.cdi.ValidationExtension. This happens implicitly within a Java EE 7 runtime environment or explicitly by adding the hibernate-validator-cdi artifact - see Section 1.1.2, “CDI”

You can see an example in Example 10.6, “CDI managed beans with method-level constraints”.

Example 10.6. CDI managed beans with method-level constraints

package org.hibernate.validator.referenceguide.chapter10.cdi.methodvalidation;

@ApplicationScoped
public class RentalStation {

	@Valid
	public RentalStation() {
		//...
	}

	@NotNull
	@Valid
	public Car rentCar(
			@NotNull Customer customer,
			@NotNull @Future Date startDate,
			@Min(1) int durationInDays) {
		//...
	}

	@NotNull
	List<Car> getAvailableCars() {
		//...
	}
}

package org.hibernate.validator.referenceguide.chapter10.cdi.methodvalidation;

@RequestScoped
public class RentCarRequest {

	@Inject
	private RentalStation rentalStation;

	public void rentCar(String customerId, Date startDate, int duration) {
		//causes ConstraintViolationException
		rentalStation.rentCar( null, null, -1 );
	}
}

Here the RentalStation bean hosts several method constraints. When invoking one of the RentalStation methods from another bean such as RentCarRequest, the constraints of the invoked method are automatically validated. If any illegal parameter values are passed as in the example, a ConstraintViolationException will be thrown by the method interceptor, providing detailed information on the violated constraints. The same is the case if the method’s return value violates any return value constraints.

Similarly, constructor constraints are validated automatically upon invocation. In the example the RentalStation object returned by the constructor will be validated since the constructor return value is marked with @Valid.

10.3.2.1. Validated executable types

Bean Validation allows for a fine-grained control of the executable types which are automatically validated. By default, constraints on constructors and non-getter methods are validated. Therefore the @NotNull constraint on the method RentalStation#getAvailableCars() in Example 10.6, “CDI managed beans with method-level constraints” gets not validated when the method is invoked.

You have the following options to configure which types of executables are validated upon invocation:

Configure the executable types globally via the XML descriptor META-INF/validation.xml; see Section 7.1, “Configuring the validator factory in validation.xml” for an example
Use the @ValidateOnExecution annotation on the executable or type level

If several sources of configuration are specified for a given executable, @ValidateOnExecutionn on the executable level takes precedence over `@ValidateOnExecution on the type level and @ValidateOnExecution generally takes precedence over the globally configured types in META- INF/validation.xml.

Example 10.7, “Using @ValidateOnExecution” shows how to use the @ValidateOnExecution annotation:

Example 10.7. Using @ValidateOnExecution

package org.hibernate.validator.referenceguide.chapter10.cdi.methodvalidation.configuration;

@ApplicationScoped
@ValidateOnExecution(type = ExecutableType.ALL)
public class RentalStation {

	@Valid
	public RentalStation() {
		//...
	}

	@NotNull
	@Valid
	@ValidateOnExecution(type = ExecutableType.NONE)
	public Car rentCar(
			@NotNull Customer customer,
			@NotNull @Future Date startDate,
			@Min(1) int durationInDays) {
		//...
	}

	@NotNull
	public List<Car> getAvailableCars() {
		//...
	}
}

Here the method rentCar() won’t be validated upon invocation because it is annotated with @ValidateOnExecution(type = ExecutableType.NONE). In contrast, the constructor and the method getAvailableCars() will be validated due to @ValidateOnExecution(type = ExecutableType.ALL) being given on the type level. ExecutableType.ALL is a more compact form for explicitly specifying all the types CONSTRUCTORS, GETTER_METHODS and NON_GETTER_METHODS.

Tip

Executable validation can be turned off globally by specifying <executable-validation enabled="false"/> in META-INF/validation.xml. In this case, any @ValidateOnExecution annotations are ignored.

Note that when a method overrides or implements a super-type method the configuration will be taken from that overridden or implemented method (as given via @ValidateOnExecution on the method itself or on the super-type). This protects a client of the super-type method from an unexpected alteration of the configuration, e.g. disabling validation of an overridden executable in a sub-type.

In case a CDI managed bean overrides or implements a super-type method and this super-type method hosts any constraints, it can happen that the validation interceptor is not properly registered with the bean, resulting in the bean’s methods not being validated upon invocation. In this case you can specify the executable type IMPLICIT on the sub-class as shown in Example 10.8, “Using ExecutableType.IMPLICIT”, which makes sure that all required metadata is discovered an the validation interceptor kicks in when the methods on ExpressRentalStation are invoked.

Example 10.8. Using ExecutableType.IMPLICIT

package org.hibernate.validator.referenceguide.chapter10.cdi.methodvalidation.implicit;

@ValidateOnExecution(type = ExecutableType.ALL)
public interface RentalStation {

	@NotNull
	@Valid
	Car rentCar(
			@NotNull Customer customer,
			@NotNull @Future Date startDate,
			@Min(1) int durationInDays);
}

package org.hibernate.validator.referenceguide.chapter10.cdi.methodvalidation.implicit;

@ApplicationScoped
@ValidateOnExecution(type = ExecutableType.IMPLICIT)
public class ExpressRentalStation implements RentalStation {

	@Override
	public Car rentCar(Customer customer, Date startDate, @Min(1) int durationInDays) {
		//...
	}
}

10.4. Java EE

When your application runs on a Java EE application server such as http://wildfly.org/, you also can obtain Validator and ValidatorFactory instances via @Resource injection in managed objects such as EJBs etc., as shown in Example 10.9, “Retrieving Validator and ValidatorFactory via @Resource injection”.

Example 10.9. Retrieving Validator and ValidatorFactory via @Resource injection

package org.hibernate.validator.referenceguide.chapter10.javaee;

@Stateless
public class RentalStationBean {

	@Resource
	private ValidatorFactory validatorFactory;

	@Resource
	private Validator validator;

	//...
}

Alternatively you can obtain a validator and a validator factory from JNDI under the names "java:comp/Validator" and "java:comp/ValidatorFactory", respectively.

When your application is CDI-enabled, the injected objects are CDI-aware as well and e.g. support dependency injection in constraint validators.

10.5. JavaFX

Hibernate Validator also provides support for the unwrapping of JavaFX properties. If JavaFX is present on the classpath a ValidatedValueUnwrapper for JavaFX properties is automatically registered. In some cases, however, it is also necessary to explicitly use @UnwrapValidatedValue. This is required if the constraint validator resolution is not unique and there is a potential constraint validator for the actual JavaFX property as well as the contained property value itself. See Section 11.11.2, “JavaFX unwrapper” for examples and further discussion.