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Chapter 11. Hibernate Validator Specifics

11.1. Public API
11.2. Fail fast mode
11.3. Programmatic constraint declaration
11.4. Applying programmatic constraint declarations to the default validator factory
11.5. Advanced constraint composition features
11.5.1. Validation target specification for purely composed constraints
11.5.2. Boolean composition of constraints
11.6. Extensions of the Path API
11.7. ParameterMessageInterpolator
11.8. ResourceBundleLocator
11.9. Custom contexts
11.9.1. HibernateConstraintValidatorContext
11.9.2. HibernateMessageInterpolatorContext
11.10. ParaNamer based ParameterNameProvider
11.11. Unwrapping values
11.11.1. Optional unwrapper
11.11.2. JavaFX unwrapper
11.11.3. Unwrapping object graphs
11.12. Providing constraint definitions
11.12.1. Constraint definitions via ServiceLoader
11.12.2. Constraint definitions via ConstraintDefinitionContributor
11.13. Customizing class-loading
11.14. Time providers for @Future and @Past

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



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, org.hibernate.validator.spi.cfg

Hibernate Validator’s fluent API for constraint declaration; In org.hibernate.validator.cfg you will find the ConstraintMapping interface, in org.hibernate.validator.cfg.defs all constraint definitions and in org.hibernate.validator.spi.cfg a callback for using the API for configuring the default validator factory. 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”.


Extended constraint validator context which allows to set custom attributes for message interpolation. Section 11.9.1, “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.


A ParameterNameProvider based on the ParaNamer library, see Section 11.10, “ParaNamer based ParameterNameProvider.


Extensions to the javax.validation.Path API, see Section 11.6, “Extensions of the Path API”.


An SPI for registering additional constraint validators programmatically, see Section 11.12, “Providing constraint definitions”.


An SPI for customizing the retrieval of the current time when validating @Future and @Past, see Section 11.14, “Time providers for @Future and @Past.

org.hibernate.validator.valuehandling, org.hibernate.validator.spi.valuehandling

Classes related to the processing of values prior to thei validation, see Section 11.11, “Unwrapping values”.


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.

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.

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”.

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”.

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”.

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.

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.

If you are not bootstrapping a validator factory manually but work with the default factory as configured via META-INF/validation.xml (see Chapter 7, Configuring via XML), you can add one or more constraint mappings by creating a constraint mapping contributor. To do so, implement the ConstraintMappingContributor contract:

You then need to specify the fully-qualified class name of the contributor implementation in META-INF/validation.xml, using the property key hibernate.validator.constraint_mapping_contributor.

In case you specify a purely composed constraint - i.e. a constraint which has no validator itself but is solely made up from other, composing constraints - on a method declaration, the validation engine cannot determine whether that constraint is to be applied as a return value constraint or as a cross-parameter constraint.

Hibernate Validator allows to resolve such ambiguities by specifying the @SupportedValidationTarget annotation on the declaration of the composed constraint type as shown in Example 11.8, “Specifying the validation target of a purely composed constraint”. The @ValidInvoiceAmount does not declare any validator, but it is solely composed by the @Min and @NotNull constraints. The @SupportedValidationTarget ensures that the constraint is applied to the method return value when given on a method declaration.

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 11.9, “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.


Using ALL_FALSE as composition type implicitly enforces that only a single violation will get reported in case validation of the constraint composition fails.

Hibernate Validator provides an extension to the javax.validation.Path API. For nodes of ElementKind.PROPERTY it allows to obtain the value of the represented property. To do so, narrow down a given node to the type org.hibernate.validator.path.PropertyNode using Node#as(), as shown in the following example:

This is specifically useful to obtain the element of Set properties on the property path (e.g. apartments in the example) which otherwise could not be identified (unlike for Map and List, there is no key nor index in this case).

Hibernate Validator requires per default an implementation of the Unified EL (see Section 1.1.1, “Unified EL”) to be available. This is needed to allow the interpolation of constraint error messages using EL expressions as defined by Bean Validation 1.1.

For environments where you cannot or do not want to provide an EL implementation, Hibernate Validators offers a non EL based message interpolator - org.hibernate.validator.messageinterpolation.ParameterMessageInterpolator.

Refer to Section 4.2, “Custom message interpolation” to see how to plug in custom message interpolator implementations.


Constraint messages containing EL expressions will be returned un-interpolated by org.hibernate.validator.messageinterpolation.ParameterMessageInterpolator. This also affects built-in default constraint messages which use EL expressions. At the moment DecimalMin and DecimalMax are affected.

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:

This is useful if you for instance would like to customize the message of the @Future constraint. By default the message just is "must be in the future". Example 11.11, “Custom @Future validator with message parameters” shows how to include the current date in order to make the message more explicit.


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 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 validating them. For example, in Example 11.13, “Applying a constraint to wrapped value of a JavaFX property” a JavaFX property type is used to define an element of a domain model. The @Size constraint is meant to be applied to the string value not the wrapping Property instance.


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.

Bean properties in JavaFX 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.

For unwrapping to occur a ValidatedValueUnwrapper needs to be registered for the type requiring unwrapping. Example Example 11.14, “Implementing the ValidatedValueUnwrapper interface” shows how this schematically looks for a JavaFX PropertyValueUnwrapper. You just need to extend the SPI class ValidatedValueUnwrapper and implement its abstract methods.

The ValidatedValueUnwrapper needs also to be registered with the ValidatorFactory:

Several unwrapper implementations can be registered. During constraint validator resolution Hibernate Validator automatically checks whether a ValidatedValueUnwrapper exists for the validated value. If so, unwrapping occurs automatically. In some cases, however, constraint validator instances for a given constraint might exist for the wrapper as well as the wrapped value (@NotNull for example applies to all objects). In this case Hibernate Validator needs to be explicitly told which value to validate. This can be done via @UnwrapValidatedValue(true) respectively @UnwrapValidatedValue(false).


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.

Instead of programmatically registering ValidatedValueUnwrapper types, 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).

Bean Validation allows to (re-)define constraint definitions via XML in its constraint mapping files. See Section 7.2, “Mapping constraints via constraint-mappings for more information and Example 7.2, “Bean constraints configured via XML” for an example. While this approach is sufficient for many use cases, it has it shortcomings in others. Imagine for example a constraint library wanting to contribute constraint definitions for custom types. This library could provide a mapping file with their library, but this file still would need to be referenced by the user of the library. Luckily there are better ways.


The following concepts are considered experimental at this time. Let us know whether you find them useful and whether they meet your needs.

While the service loader approach works in many scenarios, but not in all (think for example OSGi where service files are not visible), there is yet another way of contributing constraint definitions. You can provide one or more implementations of ConstraintDefinitionContributor to HibernateConfiguration during bootstrapping of the ValidatorFactory - see Example 11.20, “Using ConstraintDefinitionContributor to register constraint definitions”.

Instead of programmatically registering ConstraintDefinitionContributor instances, the fully-qualified classnames of one or more implementations can be specified via the property hibernate.validator.constraint_definition_contributors. This can be useful when configuring the default validator factory using META-INF/validation.xml (see Chapter 7, Configuring via XML).


One use case for ConstraintDefinitionContributor is the ability to specify an alternative constraint validator for the @URL constraint. Historically, Hibernate Validator’s default constraint validator for this constraint uses the java.net.URL constructor to validate an URL. However, there is also a purely regular expression based version available which can be configured using a ConstraintDefinitionContributor:

Using a ConstraintDefinitionContributor to register a regular expression based constraint definition for @URL

HibernateValidatorConfiguration configuration = Validation
	.byProvider( HibernateValidator.class )

	new ConstraintDefinitionContributor() {
		public void collectConstraintDefinitions(ConstraintDefinitionBuilder builder) {
			builder.constraint( URL.class )
				.includeExistingValidators( false )
				.validatedBy( RegexpURLValidator.class );

There are several cases in which Hibernate Validator needs to load resources or classes given by name:

By default Hibernate Validator tries to load these resources via the current thread context classloader. If that’s not successful, Hibernate Validator’s own classloader will be tried as a fallback.

For cases where this strategy is not appropriate (e.g. modularized environments such as OSGi), you may provide a specific classloader for loading these resources when bootstrapping the validator factory:

In the case of OSGi, you could e.g. pass the loader of a class from the bundle bootstrapping Hibernate Validator or a custom classloader implementation which delegates to Bundle#loadClass() etc.


Call ValidatorFactory#close() if a given validator factory instance is not needed any longer. Failure to do so may result in a classloader leak in cases where applications/bundles are re-deployed and a non-closed validator factory still is referenced by application code.

By default the current system time is used when validating the @Future and @Past constraints. In some cases it can be necessary though to work with another "logical" date rather than the system time, e.g. for testing purposes or in the context of batch applications which may require to run with yesterday’s date when re-running a failed job execution.

To address such scenarios, Hibernate Validator provides a custom contract for obtaining the current time, TimeProvider. Example 11.22, “Using a custom TimeProvider shows an implementation of this contract and its registration when bootstrapping a validator factory.

Alternatively, you can specify the fully-qualified classname of a TimeProvider implementation using the property hibernate.validator.time_provider when configuring the default validator factory via META-INF/validation.xml (see Chapter 7, Configuring via XML).