Problem with getting userdata from codeigniter session which has been stored in DB

[eluser]Unknown[/eluser]
Hi,

I just enabled saving sessions in DB:

Code:

$login_info=array('logged_in_user_id' => $user_result['u_id'],
'logged_in_username'=> $user_result['u_username']);

$this->session->set_userdata('login',$login_info); // after this the session will be stored in db but I cant have access to it..

But I have problem with this code:

Code:

if(!empty($this -> session -> userdata('login')))
{
    echo "login true";
} else {
    echo "login false"; // I always get this one!
        }

according to my above explanation:

1- is it a secure way for manipulating login process in codeigniter?
2- What should I do to get the db session data and get rid of the problem above?

Your answer is appreciated,

Warm regards