Proper usage of controller and model mvc

Question

i am currently working on a mvc based project.I saw people using models n controllers in different ways,im wondering which one is the correct method according to mvc principles

Method-1:

controller:

  public ActionResult index()
    {
  return View();
    }

public string save ()
  {
return null;
  }

public string Update()
 {
return null;
 }

model:

 public string xx {get;set;}
   public string yy {get;set;}

Method-2:

controller:

public ActionResult index()
{
return View();
}

model:

 public string xx {get;set;}
public string yy {get;set;}

 public string save ()
      {
    return null;
      }

    public string Update()
     {
    return null;
     }

Answer 1

I would say neither is correct though method 2 is closer to it.

You should have your logic in a separate service which is consumed by your controllers.

Example:

public ActionResult DoStuff() {
    var model = Service.save();
    return View(model);
}

public class Model {
    public string xx { get; set; }
    public string yy { get; set; }
}

public class Service 
{
    public string save ()
    {
        return null;
    }

    public string Update()
    {
        return null;
    }
}

Neither the controllers or the models should have business logic in them. They should only have a single responsibility. The model stores data that is returned by the controller. The controller simply transforms the data it receives from the service into a model.

Answer 2

Method 1.because Save /Update is Action Method which should be within Controller and not Model.