Session data gone after redirect in CI - codeigniter

Question

i need your help.
I used the session to record the user selected business type in CI. For example,$this->ci->session->set_userdata('biztype','food'). When user login,it works ok. However, once the user logout, session will be destroyed in the function logout().So i set the userdata again in the function logout().You can view the code below:
function logout()
{
$biztype = $this->ci->session->userdata('biztype');
$this->delete_autologin();
$this->ci->session->set_userdata(array('user_id' => '', 'username' => '', 'status' => ''));
$this->ci->session->sess_destroy();
$this->ci->session->set_userdata('biztype',$biztype);
//echo $this->ci->session->userdata('biztype'); //here, i can get biztype that i want
}
However,when i logout and redirect to homepage, i cant get the userdata('biztype') and my session_id have changed.
Thanks for the help.

Answer 1

This is straight from CodeIgniter User Guide:
Destroying a Session
To clear the current session:
$this->session->sess_destroy();
Note: This function should be the last one called, and even flash
variables will no longer be available. If you only want some items
destroyed and not all, use unset_userdata().
So no, you cannot destroy a session then add user_data to it, you need to reload / redirect then once the NEW session is established add data.
Try using cookies for peristance, or use the mentioned unset_userdata() fn.

Answer 2

$this->session->sess_destroy() ;
This function should be called only at the end of the execution. For unsetting data (as you're trying to do) it's better to use unset_userdata method. See how you should implement that:
$unset_items = array('user_id' => '', 'username' => '', 'status' => '') ;
$this->ci->session->unset_userdata( $unset_items ) ;

Answer 3

$email = "abc#gmail.com";
///set the session
use the set_userdata function and include the session library
$this->load->library('session');
$this->session->set_userdata('session name',Value);
i.e.
$this->session->set_userdata('email', $email);
//unset the session
$this->session->unset_userdata('session name');
i.e.
$this->session->unset_userdata('email');