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ASP.NET MVC Basics

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Adding an Action to a Controller

3:16 with James Churchill

The next change that we need to make to our controller, is to add a method to it. Well, not just *any* method—an “action” method.

Follow Along

To follow along commiting your changes to this course, you'll need to fork the aspnet-comic-book-gallery repo. Then you can clone, commit, and push your changes to your fork like this: 

git clone <your-fork>
cd aspnet-comic-book-gallery
git checkout tags/v2.2 -b adding-an-action-to-a-controller

Additional Learning

For more information about methods and access modifiers check out these pages on MSDN.

Keyboard Shortcuts

  • F5 - Start debugging (i.e. build and run your website/project)
  • CTRL+S - Save Current File

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    The next change that we need to make to our controller is to add a method to it. 0:00
    Well, not just any method, an action method. 0:04
    What is an action method? 0:08
    Every public method on a controller is an action method. 0:10
    They're responsible for 0:13
    performing any actions that are required to prepare a response for a request. 0:14
    Let's add a public method to our controller using the name Detail. 0:20
    If we want to return content for 0:27
    our response, we need our action method to have a return type other than void. 0:28
    For now let's use the string data type for our return type and 0:33
    return the string literal, Hello from the comic books controller. 0:38
    Okay, now that we have our controller set up, let's try again to run our website. 0:45
    Visual Studio will build the project, open up your selected browser, which for 0:52
    me is Google Chrome, and browse to the root of the website. 0:56
    Bummer, we still get the same 404 error. 1:00
    In order to understand why we're still getting this error, 1:04
    we need to talk about how MVC associates URLs with controller actions. 1:07
    But, for now, 1:12
    I'm just going to show how to resolve this issue without giving you an explanation. 1:13
    Don't worry, we'll cover all of the details in the next video. 1:18
    Let's click into the address bar and 1:22
    type the URL /comicbooks/detail and press Enter. 1:24
    And now, we can see our content. 1:32
    Before we end this video, let's try an experiment to see if the public 1:34
    access modifier is required on either the controller class or the action method. 1:38
    Let's close the browser and stop the website. 1:43
    First, let's remove the public access modifier on the class, 1:47
    save the file, and rerun our website. 1:52
    Remember we need to browse to the URL /comic books/detail. 1:57
    That's interesting. 2:03
    Now we get a 404 error instead of the expected content. 2:04
    Let's switch back to Visual Studio, stop the website, and 2:08
    add the public access modifier back to the class. 2:13
    When we rerun the website, Visual Studio will open another tab in Chrome. 2:17
    Go ahead and close that tab and refresh the previously open tab. 2:22
    Great, now our content is back. 2:27
    So what does this tell us? 2:30
    Controller classes need to be public. 2:32
    Otherwise NVC won't be able to find and use them. 2:35
    We could run the same experiment with our action method. 2:39
    But I'll save us some time. 2:42
    Action methods need to be public too, not surprisingly for 2:44
    the same reason why we had to make the controller class public. 2:48
    If our action methods aren't public, NVC won't be able to find and call them. 2:51
    If you're using GitHub, let's commit our changes. 2:56
    Enter a commit message of Added Detail 2:59
    action method and click the Commit All button. 3:03
    In the next video let's pull back the covers and 3:09
    take a look at how NVC associates URLs with controller actions. 3:11

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