how does asp.net mvc relate a view to a controller action?

Question

I have opened a sample ASP.NET MVC project.

In HomeController I have created a method (action) named MethodA

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

I have right clicked on MethodA and created a new view called MethodA1

Re-did it and created a new view called MethodA2 .

1. How is this magical relationship done? I looked for the config to tell the compiler that views MethodAX are related to action MethodA , but found none.

2. What view will the controller return when MethodA is called?

Answer 1

The convention is that if you don't specify a view name, the corresponding view will be the name of the action. So:

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

will render ~/Views/ControllerName/MethodA.cshtml .

But you could also specify a view name:

public ActionResult MethodA()
{
    return View("FooBar");
}

and now the ~/Views/ControllerName/FooBar.cshtml view will be rendered.

Or you could even specify a fully qualified view name which is not inside the views folder of the current controller:

public ActionResult MethodA()
{
    return View("~/Views/Foo/Baz.cshtml");
}

Now obviously all this assumes Razor as view engine. If you are using WebForms, replace .cshtml with .aspx or .ascx (if you are working with partials).

For example if there is no view it will even tell you where and in what order is looking for views:

Remember: ASP.NET MVC is all about convention over configuration.

Answer 2

The MVC framework use convention over configuration. The framework calls the ExecuteResult on the ViewResult object (created by the return View();). The framework by convention then looks in a number of locations to find a view

If you are using areas the framework will look in the following locations for a view.

• /Areas//Views/ControllerName/ViewName.aspx
• /Areas//Views/ControllerName/ViewName.ascx
• /Areas//Views/Shared/ViewName.aspx
• /Areas//Views/Shared/ViewName.ascx
• /Areas//Views/ControllerName/ViewName.cshtml
• /Areas//Views/ControllerName/ViewName.vbhtml
• /Areas//Views/Shared/ViewName.cshtml
• /Areas//Views/Shared/ViewName.vbhtml

Without areas (or if you are using areas and no view has been found) the framework will look at the following locations

• /Views/ControllerName/ViewName.aspx
• /Views/ControllerName/ViewName.ascx
• /Views/Shared/ViewName.aspx
• /Views/Shared/ViewName.ascx
• /Views/ControllerName/ViewName.cshtml
• /Views/ControllerName/ViewName.vbhtml
• /Views/Shared/ViewName.cshtml
• /Views/Shared/ViewName.vbhtml

As soon as the Framework tests a location and finds a file, then the search stops, and the view that has been found is used to render the response to the client.

There are a number of overriden versions of the View method. The most common one is to render a specific view, outside of the framework convention, by calling it by name. For example

return View("~/Views/AnotherIndex.cshtml");

As an interesting footnote, the framework looks for legacy ASP, C# and VB Razor views (aspx, ascx, cshtml and vbhtml) even though you have a specific view engine.

Answer 3

I was looking for the same and I just made a couple of tests and figured out. It doesn't save anywhere. To understand how it works; just do these steps:

In your controller, right click, Add View Then enter a different View Name and Ctrl F5 you will get Server error in application.

For example if you right click , Add View in following Index action method and type "Index2" in View name, you will get the error.

public class TestController : Controller
{
    // GET: Test
    public ActionResult Index()
    {
        return View();
    }
}

So basically there is a 1-1 matching between action name and View name. And you cannot add view for the same method so there is no need to save in a config file.

Now change the view file name in Visual Studio from Index2.cshtml to Index.cshtml then Ctrl+F5. You should see it is working.

Answer 4

In MVC controller action is not bound to view. It uses delegate mechanism to pickup the view.

Model Binding(Mapping)