Implement validation in Spring Data REST.
Spring Data REST is a framework that helps developers to build hypermedia-driven REST web services. It is built on top of the Spring Data project and makes it easy to build hypermedia-driven REST web services that connect to Spring Data repositories – all using HAL as the driving hypermedia type.
In this article, we will look at how to implement validation in Spring Data REST.
There are two @Entity classes, Author and Book. Both classes are accompanied by JpaRepository classes - AuthorRepository and BookRepository.
While Author and Book are standard JPA entities, their repositories are annotated with @RepositoryRestResource to expose them as REST resources.
link:src/main/java/zin/rashidi/boot/data/rest/book/AuthorRepository.java[role=include]link:src/main/java/zin/rashidi/boot/data/rest/book/BookRepository.java[role=include]We will implement a validation that ensures that Author in Book is not INACTIVE. To do this, we will create a custom validator class, BeforeCreateBookValidator.
link:src/main/java/zin/rashidi/boot/data/rest/book/BeforeCreateBookValidator.java[role=include]As we can see, the validator class implements Validator interface and overrides supports and validate methods. The supports method checks if the class is Book and the validate method checks if the Author is INACTIVE. Next we will inform Spring about our Validator through BookValidatorConfiguration.
link:src/main/java/zin/rashidi/boot/data/rest/book/BookValidatorConfiguration.java[role=include]Now, Spring is aware that the Validator will be executed before creating a Book.
We will perform a POST request to create a Book with an Author that is INACTIVE. The request will be rejected with 400 Bad Request response.
link:src/test/java/zin/rashidi/boot/data/rest/book/CreateBookTests.java[role=include]
link:src/test/java/zin/rashidi/boot/data/rest/book/CreateBookTests.java[role=include]Full implementation of the test can be found in CreateBookTests.