Constructor session validation for different functions

What you need to do is set up a base controller that will look after the session for you and split your logged in controllers from your logged out ones via inheritance.

My suggestion for you is to have a look at Phil Sturgeon’s post on Keeping It Dry. In his post, Phil explains the basics on how to implement controllers in such a way that the parent controller will look after sessions so you don’t have to check it every time.

As an example:

MY_Controller:

class MY_Controller extends CI_Controller{
    function __construct(){
        parent::__construct();
        //do things in here that ALL controllers should do.
    }
}

MY_In_Controller:

class MY_In_Controller extends MY_Controller{
    function __construct(){
        parent::__construct();
        //if user doesnt have the session redirect them out NOW!
    }
}

MY_Out_Controller:

class MY_Out_Controller extends MY_Controller{
    function __construct(){
        parent::__construct();
        //if the user has the session, redirect them in NOW.
    }
}

Login Controller:

class Login extends MY_Out_Controller{
    function __construct(){
        parent::__construct();
    }

    function index(){
        //folks that have a session (already logged in) will never even get here.
        //because the parent class MY_Out_Controller already redirected them back in.
    }
}

Manage Controller:

class Manage extends MY_In_Controller{
    function __construct(){
        parent::__construct();
    }

    function index(){
        //folks that don't a session (logged out) will never even get here.
        //because the parent class MY_In_Controller already redirected them out.
    }
}

In short, don’t write your session checks directly in controllers. You’ll be writing it too often and violating the DRY Principle.

Update: I recommend revamping Phil’s method by using Shane Pearson’s method in CodeIgniter’s Base Classes Revisited.