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