Validation

A good service always validates data before processing it. In this section, we will look at the Bean Validation API and use its reference implementation to implement validation in our services.

The Bean Validation API provides a number of annotations that can be used to validate beans. The JSR 349 specification defines Bean Validation API 1.1. Hibernate-validator is the reference implementation; both are already defined as dependencies in the spring-boot-web-starter project:

• hibernate-validator-5.2.4.Final.jar

• validation-api-1.1.0.Final.jar

We will create a simple validation for the createTodo service method.

Creating validations involves two steps:

1. Enabling validation on the controller method.

2. Adding validations on the bean.

Enabling Validation on the Controller Method

It's very simple to enable validation on the controller method. The following snippet shows an example:

    @RequestMapping(method = RequestMethod.POST, 
    path = "/users/{name}/todos")
    ResponseEntity<?>...