Overriding Default Methods in Spring Data Repositories

Spring Data provides nice template for standard CRUD methods and the default repository implementations provide support for a variety of back-end data stores. This eliminates the need to create boilerplate code in the application and saves a lot of time.

Adding custom behavior to Spring Data repositories

Implement Custom Behavior

interface UserRepositoryCustom {

  public void someCustomMethod(User user);
}

class UserRepositoryImpl implements UserRepositoryCustom {

  public void someCustomMethod(User user) {
    // Your custom implementation
  }
}

Let Spring know about the custom behavior

public interface UserRepository extends JpaRepository<User, Long>, UserRepositoryCustom {

  // Declare query methods here
}

Selective CRUD operations

By default, Spring Data provides the CRUD operations in org.springframework.data.repository.CrudRepository. Implementing this interface allows complete control of these methods.

But when directly implementing org.springframework.data.repository.Repositoryinterface, two CRUD methods must be provided.

1. findOne
2. save

The class org.springframework.data.repository.support.ReflectionRepositoryInvoker checks for the existence of these methods in the provided repository implementation. If not found, it will raise an exception.