This Controller Layer is the responsible for controlling the application flow and interaction between the Model and the View. Controllers are the brains of an ASP.NET MVC application, requesting data from the Model layer and choosing the correct method of getting that data to the user. Note that the Controller does not perform any of this work directly, its real job is to delegate as much as possible to the model and view layers so that they can do the real work. This article will show you how to create a Controller in ASP.NET MVC 4 application.

 Create New Controller

To create a Controller class, In Solution Explorer right click the Controller folder then select Add > Controller.

Name your New Controller

    Here one thing you should remember that all Controllers must be named by using “Controller” suffix. In this example I’m going name our new Controller as “HomeController”. Leave the default template as Empty MVC Controller. 

Notice the Controller folder in Solution Explorer, A new HomeController.cs class has been created.

This Controller class contains action methods that will render View pages. When we have created new Controller class, it has default action method and it returns View. In most cases a Controller action method returns a ViewResult.

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.Mvc;

namespace MVC4_DEMO.Controllers

{

    public class HomeController : Controller

    {

        //

        // GET: /Home/

         public ActionResult Index()

        {

            return View();

        }

    }

}

ASP.NET MVC invokes different Controller classes and its action methods depend on the incoming URL. 

Pattern: [Controller]/[ActionName]/[Parameters]

Example: http://localhost/Home/Welcome/

The first part of the URl invokes a Controller class, The second part of the URl invokes the action method in the Controller class.

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.Mvc;

namespace MVC_DEMO.Controllers

{

    public class HomeController : Controller

    {

        //

        // GET: /Home/

         public string Index()

        {

            return "This is the default action";

        }

        // GET: /Home/Welcome/

         public string Welcome()

        {

            return "This is the Welcome action method";

        }

    }

}

First let’s run the application on browser. By default it invokes index() function on HomeController. So, the question is, where is this mapping defined. The mapping is defined in Global.asax. Notice that in Global.asax we have RegisterRoutes() method.

RouteConfig.RegisterRoutes(RouteTable.Routes);

Right click on this method, and select "Go to Definition". Notice the implementation of RegisterRoutes() method in RouteConfig class.

Let’s invoke Welcome() action method that we have defined in HomeController class. Now it return value which we have assigned in that action method.

Then let’s invoke third action method User() with parameter. Now pass id in the URL as shown below and press enter.

I hope you understand the functionality of the Controller. Please comment below if is there any confusion or anything I missed to explain in this article.

Thanks for reading..!! :)