How to add custom method to Spring Data JPA

Question

I am looking into Spring Data JPA. Consider the below example where I will get all the crud and finder functionality working by default and if I want to customize a finder then that can be also done easily in the interface itself.

@Transactional(readOnly = true)
public interface AccountRepository extends JpaRepository<Account, Long> {

  @Query("<JPQ statement here>")
  List<Account> findByCustomer(Customer customer);
}

I would like to know how can I add a complete custom method with its implementation for the above AccountRepository? Since its an Interface I cannot implement the method there.

Answer 1

You need to create a separate interface for your custom methods:

public interface AccountRepository 
    extends JpaRepository<Account, Long>, AccountRepositoryCustom { ... }

public interface AccountRepositoryCustom {
    public void customMethod();
}

and provide an implementation class for that interface:

public class AccountRepositoryImpl implements AccountRepositoryCustom {

    @Autowired
    @Lazy
    AccountRepository accountRepository;  /* Optional - if you need it */

    public void customMethod() { ... }
}

See also:

• 4.6 Custom Implementations for Spring Data Repositories

• Note that the naming scheme has changed between versions. See https://stackoverflow.com/a/52624752/66686 for details.