How should I encapsulate my MVC-Action in order to avoid code duplication?

Question

I have two classes - MVC-Controlles in this particular case – that have one common controller action (a JSON action that will be called from JavaScript). Because of code duplication, I would like to put this action in a parent controller class. We already have a controller base class that inherits from Controller and is used as base class, with common functionality, from 6 other Controllers. My JSON action is actually common only for 2 controllers, so I think that it’s not a good idea to put my JSON action in the base controller that is already used by the other 6 controllers. Here’s the existing class hierarchy graph:

Existing Controller class hierarchy

Where should I put my JSON action in order to avoid code duplication? My idea is to inherit the class ControllerBase – let’s say ControllerBaseExtended – and to place my JSON action in here. So now, my 2 Controllers can inherit from ControllerBaseExtended instead of ControllerBase. This is how the class hierarchy would look like at the end:

Final Controller class hierarchy

Is there any better way to solve this problem?

Answer 1

Instead of creating another base controller, extract code from both actions into another class, e.g. JsonActionProcessor. Then you will need to call that implementation.

public class JsonActionHelper
{
    public JsonResult Something()
    {
        //do something common
        return new JsonResult();
    }
}

Then you can call it from your actions

public JsonResult Action1()
{
    return new JsonActionHelper().Something();
}

public JsonResult Action2()
{
    return new JsonActionHelper().Something();
}

If you have UnitTests then you should extract interface from JsonActionHelper and inject it into your Controllers.

However if you have 2 identical actions, why just not to have one action and call it via JavaScript from different views?