CodeIgniter - How to check session to be used at every methods

Question

Let say at my controller named Book, I have many methods, such as get_book(); read_book(); remove_book();

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Answer 1

You don't necessarily need to do that. Simply put the login check code in the constructor and you're all set!

class Book extends CI_Controller
{
    public function __construct()
    {
        if ($this->is_logged_in())
        {
            // redirect to home
        }
    }

    public function get_book()
    {
        ...
    }

    // The rest of the code...
}

Answer 2

You can use the method in constructor of controller, like:

if ( ! $this->session->userdata('logged_in'))
    {   
            redirect('login');
    }

Answer 3

Create a file called MY_controller.php (the prefix can be edited in config file) in /application/core:

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');

class MY_Controller extends CI_Controller {


    function __construct()
    {

        parent::__construct();

        //Initialization code that affects all controllers
    }

}


class Public_Controller extends MY_Controller {

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

        //Initialization code that affects Public controllers. Probably not much needed because everyone can access public.
    }

}

class Admin_Controller extends MY_Controller {

    function __construct()
    {
        parent::__construct();
        //Initialization code that affects Admin controllers I.E. redirect and die if not logged in or not an admin
    }

}

class Member_Controller extends MY_Controller {

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

        //Initialization code that affects Member controllers. I.E. redirect and die if not logged in
    }

}

Then anytime you create a new controller, you decide what access it requires

    class Book extends Member_Controller {

        //Code that will be executed, no need to check anywhere if the user is logged in. 
        //The user is guaranteed to be logged in if we are executing code here.

//If you define a __construct() here, remember to call parent::__construct();
    }

This cuts code duplication a lot, since if you need another member controller other than Book you can just extend the Member_Controller. Instead of having to do the checks in all of them.