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Chapter 22. Additional modules

Table of Contents

22.1. Bean Validation
22.1.1. Adding Bean Validation
22.1.2. Configuration
22.1.3. Catching violations
22.1.4. Database schema
22.2. Hibernate Search
22.2.1. Description
22.2.2. Integration with Hibernate Annotations

Hibernate Core also offers integration with some external modules/projects. This includes Hibernate Validator the reference implementation of Bean Validation (JSR 303) and Hibernate Search.

Bean Validation standardizes how to define and declare domain model level constraints. You can, for example, express that a property should never be null, that the account balance should be strictly positive, etc. These domain model constraints are declared in the bean itself by annotating its properties. Bean Validation can then read them and check for constraint violations. The validation mechanism can be executed in different layers in your application without having to duplicate any of these rules (presentation layer, data access layer). Following the DRY principle, Bean Validation and its reference implementation Hibernate Validator has been designed for that purpose.

The integration between Hibernate and Bean Validation works at two levels. First, it is able to check in-memory instances of a class for constraint violations. Second, it can apply the constraints to the Hibernate metamodel and incorporate them into the generated database schema.

Each constraint annotation is associated to a validator implementation responsible for checking the constraint on the entity instance. A validator can also (optionally) apply the constraint to the Hibernate metamodel, allowing Hibernate to generate DDL that expresses the constraint. With the appropriate event listener, you can execute the checking operation on inserts, updates and deletes done by Hibernate.

When checking instances at runtime, Hibernate Validator returns information about constraint violations in a set of ConstraintViolations. Among other information, the ConstraintViolation contains an error description message that can embed the parameter values bundle with the annotation (eg. size limit), and message strings that may be externalized to a ResourceBundle.

By default, no configuration is necessary.

The Default group is validated on entity insert and update and the database model is updated accordingly based on the Default group as well.

You can customize the Bean Validation integration by setting the validation mode. Use the javax.persistence.validation.mode property and set it up for example in your persistence.xml file or your hibernate.cfg.xml file. Several options are possible:

  • auto (default): enable integration between Bean Validation and Hibernate (callback and ddl generation) only if Bean Validation is present in the classpath.

  • none: disable all integration between Bean Validation and Hibernate

  • callback: only validate entities when they are either inserted, updated or deleted. An exception is raised if no Bean Validation provider is present in the classpath.

  • ddl: only apply constraints to the database schema when generated by Hibernate. An exception is raised if no Bean Validation provider is present in the classpath. This value is not defined by the Java Persistence spec and is specific to Hibernate.


You can use both callback and ddl together by setting the property to callback, dll

<persistence ...>
  <persistence-unit ...>
      <property name="javax.persistence.validation.mode"
                value="callback, ddl"/>

This is equivalent to auto except that if no Bean Validation provider is present, an exception is raised.

If you want to validate different groups during insertion, update and deletion, use:

  • javax.persistence.validation.group.pre-persist: groups validated when an entity is about to be persisted (default to Default)

  • javax.persistence.validation.group.pre-update: groups validated when an entity is about to be updated (default to Default)

  • javax.persistence.validation.group.pre-remove: groups validated when an entity is about to be deleted (default to no group)

  • org.hibernate.validator.group.ddl: groups considered when applying constraints on the database schema (default to Default)

Each property accepts the fully qualified class names of the groups validated separated by a comma (,)


You can set these properties in hibernate.cfg.xml, hibernate.properties or programmatically.