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Adding an Action to a Controller
3:16The 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.
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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