在Codeigniter中定义全局（动态）变量

Question

Is there a way of defining a dynamic global variable in Codeigniter? I need to regularly use:

$this->session->userdata('user_id')

in my code, and I really don't want to have to type this out all the time. What I've done in another project is use something like:

$this->mid = $this->session->userdata('user_id')

in a controller's constructor, making it accessible for every method in that controller, but I then have to redefine it in every other controller constructor. I know I sound lazy, but I just want to make the best DRY code possible. I know you can specify static variables in the config/config.php file, but these variables are dynamic - so I don't think you'll have access to the $this object (or something) in that file.

Is there anyway of making such a session variable global?

Answer 1

Create a custom controller MY_Controller.php:

<?php
    class MY_Controller extends Controller {

        var user_id = '';

        function __construct() {
            parent::__construct();

            $this->user_id = $this->session->userdata('user_id');
        }
    }
?>

And extend that controller by your controllers, for example the controller Welcome.php:

<?php
    class Welcome extends MY_Controller {

        function __construct() {
            parent::__construct();
        }

        function index() {
            var_dump( $this->user_id );
        }
    }
?>

You can set the global variable in MY_Controller and use it on every controller that extends the custom one.