CODEWITHSUNDEEP
c#.netweb-applicationsasp.net-mvc-4
Taylor Jones
Taylor Jones

Reputation: 163

Understanding MVC4 Controllers

I'm fairly new to the .net Framework and the whole MVC programming philosophy. Could someone clarify and give me a basic explanation how controllers interact with sites using C#? I understand how to code in C#, and I understanding some aspects of the framework, but I don't see how they all tie together.

Upvotes: 5

Views: 2260

Answers (4)

Ebrahim Byagowi
Ebrahim Byagowi

Reputation: 11218

Controller in ASP.NET MVC is an object that handel your app logic in response of requests. It will be created per request (e.g. a HTTP request) and will be available until response created by View layer. After that it will be an unusable object (and soon GC will free its allocated memory) and for another request a new controller object must be created and so on.

I think by this definition it will be obvious why it must be lightweight and how you must use it.

Upvotes: 1

Kami
Kami

Reputation: 19407

Model - Is a data structure that represents some kind of object (usually one). It's purpose is to read, write and manage the access to the underlying object with the aim to persist application state.

View - Is the components that are used to display a visual interface to the user, perhaps using a model. It might be a simple table or a complex combination into a full web page.

Controller - Is the user driven application logic layer the sits between views and models. It handlers user interaction, loads models, and sends views to the user. It determines what model is sent to the view depending on user requests.

The overall folder structure for an application might look like this.

>> Website
     >> Controllers
     >> Models
     >> Views

In C# MVC each controller must have the suffix Controller in the name, they must extend Controller class and have a folder of the name prefix (without the Controller) in the views folder. This folder will then contain all the views related to particular actions on the controller.

Controllers can contain any number of actions defined as public functions. By default when returning a result from a controller action the name of the view must correspond with the name of the action. However you can also specify a view by name. When loading a view from a controller, it is possible to send an object as a model to the view and there by generate it's content.

Controllers can load any model and are not restricted in any way.

An Account controller defined as below with an action Login. The controller is placed in a AccountController.cs file in the /Controllers folder, and any views for this controller (Login in this instance with filename Login.cshtml) are placed in the /Views/Account folder.

Note: The naming convention has to be right as the names are used between the controllers and views to link the data.

public class AccountController : Controller
{
    public ActionResult Login(string returnUrl)
    {
        if (User.Identity.IsAuthenticated)
        {
            return RedirectToAction("Index","Site");
        }

        return View("Login", new LogOnModel());
    }
}

would be accessible via http://www.mysite.com/Account/Login. If the user is authenticated, the controller will redirect to the main site controller, if the user is not logged in then they are shown the Login view which loads data from the LogOnModel specified.

This is really just touching the surface of what is possible. Read some online information on some excellent articles by ScottGu which go into much more depth and talk you through how to use MVC.

ASP.NET MVC Framework Overview

ASP.NET MVC Framework How To - Part 1 // Part 2 // Part 3 // Part 4

Note : These articles are slightly outdated as they were written for MVC version 1 back in 2007, but the concepts of how the Models, Views and Controller interact still apply.

Upvotes: 6

David L
David L

Reputation: 33815

Controllers serve somewhat as an internal web service. They expose your server side code to your views and allow them to call the controllers. In terms of pattern, most people believe that controllers should be as thin as possible. If there is heavy lifting or other business logic, you should abstract it to another part of your application. In my eyes, controllers are there to provide the view with something to call, and then to return that data whether it be text/html, json, or xml.

Here's a great wealth of information, straight from the source: http://www.asp.net/mvc/mvc4

Specifically to the site, I'd highly recommend the tutorial. It will give you a much clearer picture of how Models, Views, and Controllers interact and depend on one another. http://www.asp.net/mvc/tutorials/mvc-4/getting-started-with-aspnet-mvc4/intro-to-aspnet-mvc-4

Upvotes: 2

marcos.borunda
marcos.borunda

Reputation: 1486

A controller is a class which has methods, those methods are called actions, you atach those actions to "views" (cshtml files).

//This is your controller
public class HomeController : Controller
{
    // This is your action
    public ActionResult Index()
    {
        return View();
    }
}

You can right click the "Index" action and select "Add View..." this will create a new view atached to that action.

In order to access that view you will do something like: localhost/Controller/Action In this case it should be: localhost/Home/Index where Home = Controller, Index = Action

You should read about the MVC pattern

Microsoft has some really good tutorials for beginers

Upvotes: 1

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