CODEWITHSUNDEEP
springdependency-injectiondependenciesdependency-management
Tonyukuk
Tonyukuk

Reputation: 6195

How to avoid dependency about at dependent objects

I have a question about Spring Environment. If I have a controller and that controller has lots of services inside in it which is dependent each other and if I change something on that controller what I should do "less" by reducing amount of codes ? By that, how I will avoid dependency problem ? ,Hope my question is clear for you .

Thank you

Upvotes: 0

Views: 169

Answers (2)

so-random-dude
so-random-dude

Reputation: 16465

controller has lots of services inside in it which is dependent each other

That's a design smell right there, you might even get circular dependency problem with that kind of design. You may need to post your controller code here to get more help.

Upvotes: 0

Johnny Alpha
Johnny Alpha

Reputation: 970

My two cents:

  • Use autowired constructor injection as recommended by the Spring team. Doing this makes it very visible when your controller is getting bloated (see the next point)
  • Have no more than 3 dependencies in the constructor as suggested by Bob Martin in his book Clean Code. If you have more, then your controller is probably violating the single responsibilty principle.
  • If you want your controller to do more then you should probably put that functionality in a second controller!

A crude example:

    @RestController
    public class PetShopController {

    @Autowired private DogService dogService;
    @Autowired private CatService catService;
    @Autowired private MonkeyService monkeyService;
    @Autowired private FishService fishService;
// all three services above are dependent on the two below
    @Autowired private PetInsuranceService petInsuranceService;
    @Autowired private PetOwnerService petOwnerService; 

    //..and so on
    }

Change to:

@RestController
public class DogsController {

private DogService dogService;

//the insurance/owner services have been split into one service/pet type
private DogInsuranceService dogInsuranceService; 
private DogOwnerService dogOwnerService;

//I've used interfaces for types here
@Autowired DogsController(IPetService dogService,IInsuranceService dogInsuranceService, IOwnerService dogOwnerService) {
this.dogService = dogService;
this.dogInsuranceService = dogInsuranceService;
this.dogOwnerService = dogOwnerService;
}

//..and so on
// make similar controllers for other pets!!

}

I'd argue that it's not about reducing the amount of code, it's more about making sure each class has a single responsibility! Eg/ here Dogs do dog things like bark! Cats do cat things like meow!! As soon as you have a class with more than 3 deps/services that does both or more then that class needs to be split!!

Upvotes: 1

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