Spring Data Repository - 方法签名

Question

I have the following code:

public interface CompanyRepository extends JpaRepository<Company, String> { }

• Where can i view the methods generated by this?

• Do i have to list all the generated methods also in my service interface, before i can use them in my Controllers?

   public interface CompanyService { } 

I would liked to use the repository methods via my Service implementation class but it seems there is no way to do that.

Answer 1

Spring Data JPA instantiated your repo for you 'on the fly' (with it's magic )). You can find a repo implementation, for example, here .

So in common case it's not necessary to duplicate all these methods of your repo. Instead you should add your custom ' query methods ' to it. For example:

public interface CompanyRepo extends JpaRepository<Company, String> {
    List<Company> findAllByName(String companyName);
}

Spring (again, with its magic) implements this method for you (you can find here about how to create such methods). So you will have the repo with basic methods ( save , findAll , findById , delete etc.) and with your custom methods.

Then you can use this repo in your transactional service to implement your business logic:

@Service
@Transactional
public class CompanyService {

    private final CompanyRepo companyRepo;

    public CompanyService(CompanyRepo companyRepo) {
        this.companyRepo = companyRepo;
    }

    public Company create(CompanyDto dto) {
        Company company = dto.toCompany();
        // Some custom logic...
        return companyRepo.save(company);
    }
}

Then use the service in your controller:

@RestController
@RequestMapping("/companies")
public class CompanyController {
    private final CompanyService companyService;

    public CompanyController(CompanyService companyService) {
        this.companyService = companyService;
    }

    @PostMapping
    public ResponseEntity create(@RequestBody CompanyDto dto) {
        return ResponseEntity.ok(companyService.create(dto));
    }
}

Answer 2

They are all here: Spring Docs .

And no, do not expose them directly in your service, your service must use them; even if there is simple delegate in some cases (like find\\delete , etc).

Exposing them in your controller directly, will create a small confusion, especially when testing - since you will need to mock them, test them etc (and spring already tested them). I find it much cleaner when the controller interacts with the service only, and this for example, is enforced in our project.