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Rails Routes and Resources

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Creating a Controller

2:39 with Jay McGavren

We have a route set up that says GET requests for /pages should go to the PagesController index method. But that controller doesn't exist yet, so the request is failing. Let's create a controller to handle requests for Page resources.

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    We have a route set up that says GET requests for /pages should go to the pages 0:00
    controller index method but that controller doesn't exist yet. 0:04
    So the request is failing. 0:08
    Let's create a controller to handle requests for page resources. 0:10
    We can do that using a Rails generator. 0:13
    Just as there is a scaffold generator and 0:15
    a migration generator, there's also a controller generator. 0:18
    So in our terminal, we need to cancel out of the Rails Server if it's running, 0:21
    and then we type bin/rails generate controller. 0:27
    And then the name of the controller we want to generate. 0:31
    The name of the controller should be the plural form of your resource. 0:34
    So since this is for page resources, the plural is pages. 0:37
    Whatever you do, don't type controller on the end of the controller name. 0:42
    If you do, you'll wind up with a file name pages_controller_controller. 0:46
    And you don't want that. 0:50
    If you ever make a mistake like that, here's a handy way to undo it. 0:52
    Run the same command but replace generate with destroy. 0:55
    That will automatically delete all the misnamed files. 1:03
    Obviously the destroy subcommand is a little dangerous. 1:06
    So don't use it if you've manually added code to any of those files. 1:09
    Now let's rerun our generate command with the correct resource name, pages. 1:13
    That will automatically generate a pages_controller.rb file in your 1:19
    app/controllers subdirectory, along with our app's other controllers. 1:23
    The word controller will automatically be added onto the name for you. 1:27
    If we look at that file in our editor we see that it just defines an empty class 1:32
    named PagesController that inherits from another class named ApplicationController. 1:36
    There aren't any action methods defined yet, but 1:41
    now that the controller exists, let's try our request again and see what happens. 1:43
    We'll launch our server with bin/rails s. 1:48
    Then we'll go back to the browser and reload the page. 1:53
    The uninitialized constant PagesController error goes away. 1:56
    Instead we see an unknown action error, the action index could not be found for 2:00
    PagesController. 2:05
    Let's add that index action method now. 2:06
    In your editor, add def index, end and then save your changes. 2:09
    There's no need to restart Rails, it will load our changes automatically. 2:15
    Now let's go back to our browser and hit refresh and the route is complete. 2:19
    Rails finds the index method it was trying to route to, so 2:24
    the unknown action error goes away. 2:26
    Now there's yet another error, though. 2:29
    PagesController#index is missing a template. 2:31
    Our request is being routed to a controller action, but 2:33
    we're missing a view. 2:36
    We'll fix that next. 2:37

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