CODEWITHSUNDEEP
javaspringjpadesign-patternsspring-data-jpa
Jonas P.
Jonas P.

Reputation: 369

Crud methods in service layer using Spring Data JPA

I'm building a small application using Spring and Spring Data JPA and I need to use the CrudRepository methods in the service layer, so I made 2 classes: GenericService and GenericServiceImpl. But I don't know if this is the right or even the best approach.

Here is an example:

POJO:

@Entity
public class User {

  @Id
  private Long id;

  private String username;
}

DAO:

public interface UserDAO extends CrudRepository<User, Long> {
  User findOneByUsername(String username);
}

Generic service

public interface GenericService<T, ID extends Serializable> {
  <S extends T> S save(S entity);
}

Service

public interface UserService extends GenericService<User, Long>  {
  User findOneByUsername(String username);
}

Generic service impl.

public class GenericServiceImpl<T, ID extends Serializable> implements GenericService<T, ID> {

    @Autowired
    private CrudRepository<T, ID> repository;

    @Override
    public <S extends T> S save(S entity) {
        return repository.save(entity);
    }
}

Service Impl.

@Service
@Transactional
public class UserServiceImpl extends GenericServiceImpl<User, Long> implements UserService {

  @Autowired
  private UserDAO userDAO;

  @Override
  public User findOneByUsername(String username) {
    userDAO.findOneByUsername(username);
  }
}

Upvotes: 8

Views: 19235

Answers (1)

Mustehssun Iqbal
Mustehssun Iqbal

Reputation: 566

Yes, you're providing your own impl that's may do custom things while still reusing the Derived queries from Spring JPA's CrudRepository. I've seen that a lot. :) We need to do that if we want to do our own computation before calling the Derived methods. After all, that computation may very well be part of a repository, so it doesn't make sense to put that logic in the service. But in your scenario, if there are no such custom computations, then this indirection isn't needed. As a commenter mentioned, you should directly use the UserDao interface. :)

Upvotes: 0

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