How can I use session in a library in CodeIgniter?

Question

I want to check if user is logged in CodeIgniter by using my library in the controller's constructor.

This is my library:

class Administrator_libs {

    public function validate_authen(){
        if( $this->session->userdata('user_authen') ){
            redirect(base_url().'admin/login/');
        }   
    }
}

And this is my controller:

class Administrator extends CI_Controller {

    public function __construct(){
        parent::__construct();
        $this->load->library('administrator_libs');
        $this->administrator_libs->validate_authen();
        $this->load->model('mod_menu');
    }
}

But I get this error message:

Undefined property: Administrator_libs::$session

How can I use session in a library in CodeIgniter?

Answer 1

If you want to access any CodeIgniter library inside of your own, you must call get_instance(). This is because $this is bound to your current library and not the CodeIgniter object.

$CI =& get_instance();
if( $CI->session->userdata('user_authen') ){
    redirect(base_url().'admin/login/');
}

Please see Creating Libraries CodeIgniter Documentation. Specifically the content under Utilizing CodeIgniter Resources within Your Library

This assumes you autoload the session library in config/autoload.php, if not, you'll also need to add $CI->load->library("session"); after $CI instantiation.

IMPORTANT: =& is not a typo. It's passed by reference to save memory.