Question

   I have searched on SO about this question, but I basically haven’t found one concerning this particular scenario; hence, my reason for asking.
    I have a basic, abstract understanding of the MVC pattern: Controller calls the right Model based on the action needed; the Model contains the actual business/data logic, and the View displays the result. What I am having trouble understanding is the actual implementation.
   Originally, my assumption was this: Controller calls Model; Model processes information, and returns the data back to Controller; Controller call the View, passing this
data to the View, which simply displays it. After reading more articles on MVC, I discovered that the Model doesn’t really pass the data back to the Controller; rather, it fires an event, which allows the Controller to call the proper View.
My question centers on this event firing part:

   Q.1: Must an event really be fired? Once the Model completes its processing, and returns control to the Controller, can’t the Controller simply call the View?
   Q.2: In an actual implementation, a Model object is injected into a Controller class. So, Model object basically has no idea what Controller called it. How does it know what Controller to fire an event to? And how do we know what Controller is expecting that notification?
   Q.3: The Controller calls the View, injecting it with the current Model object, so the View can use it to obtain the needed data. Is this correct or wrong? If wrong, why is it wrong, and what is the proper way to do it?
   I have read my questions on MVC on here and other sites, viewed MVC diagrams, but I haven’t been able to really connect the dots the way it’s supposed to be connected.
   Thanks.

Answer 1

There are many way’s on how the different components on MVC are linked together. I think there is no ‘Golden Rule’.

I use it the way shown in this picture:

The creation of objects is then like this:

1. the app object creates a controller, depending on the route. The router is injected into the controller.
2. The controller creates a model, depending on the route. The model is created by a IoC container.
3. The controller creates a view, and injects the model into the view.

In my situation I can answer your questions like this:

Q1: No, I do not use events. There is no need. The controller calls the model, and when done the model has state, and can be used by the view.

Q2: I do it just the other way, the controller creates the model. The model has no knowledge about the controller, or view.

Q3: this is the way I implement it.