RESTful Java Web Services - Third Edition

Building custom validation constraints

In the previous section, we had a quick look at the built-in validation constraints offered by the Bean Validation framework. There may be cases where you may want to build your own validation constraints. The Bean Validation framework supports that as well.

The core contracts that you should implement for a custom validation constraint are as follows:

• Annotation for the custom validation constraint
• Implementation of the javax.validation.ConstraintValidatorContext interface. This class contains your custom validation logic
• Definition of a default error message

Let's build a custom validation constraint for checking whether a department with the same name already exists for a given location. This constraint ...