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Ruby on Rails 5 Basics

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The Controller

1:47 with Jay McGavren

The controller is responsible for handling the browser request. It CONTROLS the model and the view to generate a response.

When you access the list of all "Post" objects, the request gets sent to the "index" method of the "PostsController" class.

  • Rails creates the source code for controller classes in the "app/controllers/" subdirectory.
  • The "PostsController" class will be in "posts_controller.rb".
  • The request is handled by the "index" method or action (controller methods that respond to requests are sometimes called "actions").

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    This section of the log shows where Rails proceed to get requests for 0:00
    the posts path. 0:04
    The request gets sent to the index method of the PostsController class. 0:05
    The controller is responsible for handling the browser requests. 0:10
    It controls the model and the view to generate a response. 0:13
    The controller receives the request, 0:16
    loads the requested data via the model usually from a database. 0:18
    And then inserts that data into the view, which is usually an HTML page. 0:22
    The result of rendering the HTML is then returned to the browser as a response. 0:27
    Most of the code for your app including controllers, models and 0:32
    views will reside within the app sub directory. 0:35
    Rails create source files for controller classes in the app controllers directory. 0:38
    Here's the PostController class, in posts_controller.rb. 0:43
    And here's the index method or action. 0:48
    Controller methods that respond to requests are sometimes called actions. 0:51
    Doesn't look like much, but 0:55
    that's because it's mostly using the default operations to handle the request. 0:56
    First, it loads some data via the Post model class. 1:01
    It calls the Post.all method to load all post objects and 1:04
    stores them in an instance variable. 1:08
    Then the controller uses the data in that instance variable to render a view. 1:10
    By default it renders a template with the same name as the action 1:15
    within the same page layout the rest of the application uses. 1:18
    We could add an explicit call to the render method and get the same result. 1:21
    We could render the posts/index template using a layout of application. 1:25
    If we save this and then reload the page in our browser, we'll get the same result. 1:33
    So the controller loads model data by calling Post.all and 1:38
    then it renders the index view. 1:42
    Next, we'll look at that model and view in more detail. 1:44

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