MVC - reference a model from another model

Question

I've this scenario in my application:

• Controller1

  • .GetItems()

• Model1

  • .GetItems()

• Controller2

  • .GetCurrentUser()

• Model2

  • .CurrentUser

In this scenario Controller1.GetItems() calls Model1.GetItems() method. Model1.GetItems() method needs to know (for example) what is the role of the current user to build the correct list of items, and it should get it from the Model2.CurrentUser property (that stores the cached information about the current user).

Is it a good practice to acces a model from another model?

Thanks, Regards

Answer 1

You are going to run into some arguments about the best way to do this, but at the end of the day, you have two options. Either you can have the model pull the information it needs from the other model or you can have the controller pass the information needed.

Based upon what I have read, as long as the model does not have any controller logic or view logic you are good so there is nothing wrong with having the model know about other models. However, others have argued that having the controller pass the information that is needed makes the code a bit easier to document since you can see that the model requires information from somewhere else. At the end of the day though, I see both as being valid and which one you choose to use will likely come down to personal preference.

---

Design - Controller Provides Data

ModelOne

• User GetCurrentUser()

ModelTwo

• Items[] GetItems(User)

Snippet - Controller Proivdes Data

Controller {
  function doWork() {
    User user = ModelOne.GetCurrentUser();
    Items[] items = ModelTwo.GetItems(user);
  }
}

---

Design - Model Gets Data

ModelOne

• User GetCurrentUser()

ModelTwo

• Items[] GetItems()

Snippet - Model Gets Data

ModelTwo {
  Items[] GetItems() {
    User user = ModelOne.GetCurrentUser();

    ...

  }
}

Controller {
  function doWork() {
    Items[] items = ModelTwo.GetItems();
  }
}