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Chapter 3. Bean Validation Integration

3.1. Validating HTTP requests
3.1.1. Validating entity body
3.1.2. Validating resource fields
3.1.3. Validating other method parameters
3.2. Validation configuration
3.3. Using validation groups

Bean Validation (JSR-303) is a specification introduced as a part of Java EE 6. It aims to provide a standardized way of validating the domain model across all application layers.

The Seam REST module integrates with the Bean Validation specification. This allows incomming HTTP requests to be validated using this standardized mechanism.

Firstly, enable the ValidationInterceptor in the beans.xml configuration file.


<interceptors>
    <class>org.jboss.seam.rest.validation.ValidationInterceptor</class>
</interceptors>

Then, enable validation of a particular method by decorating it with the @ValidateRequest annotation.

@PUT

@ValidateRequest
public void updateTask(Task incommingTask)
{
...
}

In some cases, it is desired to have a specific group of constraints used to validate the web service parameters. These constraints are usually weaker compared to the default constraints of a domain model. Take partial updates as an example.

Consider the following example:


The Employee resource in the example above is not allowed to have the null value specified in any of its fields. Thus, the entire representation of a resource (including the department and related object graph) must be sent to update the resource.

When using partial updates, only the values of modified fields are required to be sent within the update request. Only the non-null values of the received object are updated. Therefore, two groups of constraints are needed: one for partial updates (including @Size and @Email, excluding @NotNull) and the default one (@NotNull).

A validation group is a simple Java interface:



Finally, the ValidationInterceptor is configured to validate the PartialUpdateGroup group only.