I am working on a project with a service, repository pattern. AService, ARepository, BService, BRepository. Now, however, it happens that A has a relation to B. So I have to shoot another query against the B database to merge both objects later. For example: give me all objects A and their relation to object B. Can I call the BRepository directly from the AService or should I better go via the BService? Is there a rule here according to cleanCode?

CodePudding user response：

Sure, you can. Imagine situation, when user buy something in online shop. You would need many repositories:

public  class OrderService
{
    private IUserRepository _userRepository;
    private IWareHouseRepository _wareHouseRepository;
    
    OrderService(IUserRepository userRepository,
        IWareHouseRepository wareHouseRepository)
    {
        _userRepository = userRepository;
        _wareHouseRepository = wareHouseRepository;
    }
}

I would prefer to call repository instead of service because repository is less specific. I mean calling another service ServiceB that contain desired repository can be dangerous as business logic can be added into existing service ServiceB which is not eligible for your ServiceA.

In addition, circular dependencies can be occured if we call service from another service. So try to use dependency injection. Moreover, try to program to interfaces, not implementations, I mean you can create interfaces for your service classes and use this interface from your client classes (pass the concrete implementation to the constructor).