Extending CodeIgniter's Controller

This seems to be something that everybody's writing about - and by everybody, I mean Mark Huot and Greg Aker - so I thought I'd jump in and pick up where Mark left off. By extending the core CI_Controller class you can write a small layout library that lets you automatically load views into a layout.

class MY_Controller extends CI_Controller {
    protected $data;
    protected $view;
    protected $layout;

    /**
     * Remap the CI request, running the method
     * and loading the view
     */
    public function _remap($method, $arguments) {
        if (method_exists($this, $method)) {
            call_user_func_array(array($this, $method), array_slice($this->uri->rsegments, 2));
        } else {
            show_404(strtolower(get_class($this)).'/'.$method);
        }

        $this->_load_view();
    }

    /**
     * Load a view into a layout based on
     * controller and method name
     */
    private function _load_view() {
        // Back out if we've explicitly set the view to FALSE
        if ($this->view === FALSE) { return; }

        // Get or automatically set the view and layout name
        $view = ($this->view !== null) ? $this->view . '.php' : $this->router->directory . $this->router->class . '/' . $this->router->method . '.php';
        $layout = ($this->layout !== null) ? $this->layout . '.php' : 'layouts/application.php';

        // Load the view into the data
        $this->data['yield'] = $this->load->view($view, $this->data, TRUE);

        // Display the layout with the view
        $this->load->view($layout, $this->data);
    }
}

This instantly gives us a bunch of cool functionality:

• Controller data can all be kept in $this->data, which keeps your controllers neat and allows you to pass view data through multiple methods
• The view is automatically guessed based on the controller name and method name. You'll see precisely how this works in a moment.
• The view is being loaded into a layout; defaulting to layouts/application.php.

One final thing to add is that all of these conventions can be overridden if we need to. If we don't want to load a view - we're outputting a file, or JSON or something else instead - we can simply set $this->view to FALSE. We can choose to load a specific view by setting $this->view to the view name, or load a different layout by setting $this->layout.

Here's how it looks in action:

class Gifts extends MY_Controller {

    /**
     * Automatically loads the gifts/index.php view
     */
    public function index() {
        $this->data['title'] = 'All Gifts';
        $this->data['gifts'] = $this->gift_model->get_all();
    } 

    /**
     * Loads the gifts/create.php view
     */
    public function create() {
        $this->data['title'] = 'New Gifts';
    }

    /**
     * Does not load a view
     */
    public function json() {
        $this->view = FALSE;
        die(json_encode($this->gift_model->get_all()));
    }
}

And then, in our views/layouts/application.php file we can echo the contents of the $yield variable, which will be automatically set as the contents of our view.

<h1><?= $title ?></h1>

<div id="contents">
    <?= $yield ?>
</div>

Cool, huh?