controller_class.md

The Controller Abstract class

Once a URL request triggers an action in a controller (thanks to our Router instance), this one may retrieve some data (using an instance of a model), loads whatever view file is needed, and injects into it the retrieved data. This is gonna be common logic for all controllers, so it's a good idea to create an abstract class to define this behaviour. Such a class is gonna need just two methods:

• load(string $model): which simply loads the file where we have defined whatever model class is needed, and returns an instance of it.
• render(string $view, array $data): which simply loads the view file, passing down whatever is in the data array. By the way, just adding the data as a parameter in this method, is enough to make it available in the view (yeah, it surprised me too).

For rendering the views we could have created a View class with a render method, and invoke it in the controller as View::render($index, $data);. But hey, next time ;-)

A Controller example

Let's write a Users controller to test the abstract class mentioned above:

class Users extends Controller
{
    public function index()
    {
        $userInstance = $this->load('User');
        $data = $userInstance->getUsers();
        $this->render('Users', $data);
    }
}

As you can see, the index method (known as action in MVC) is using the abstract methods to:

1. Load a model file, and instantiate the User model.
2. Load a view file, and pass down the data it got from the model.

That is known as the MVC Workflow!

In MVC, by convention, controllers are named in plural, e.g. Users, Posts, etc. Whereas models are singular, e.g. User, Post, etc.

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