Updating session vaules in CodeIgniter

Try:

$this->session->set_userdata('jezik',$data['jezik']);

codeigniter session return-value

You need to use set_userdata rather than userdata. There are two ways to do it. You can do it in a key/value type way

$this->session->set_userdata('jezik', $data['jezik']);

Or you can pass an array

$sessionData = array('jezik' => $data['jezik'])$this->session->set_userdata('jezik',$data['jezik']);

You can read more about CodeIgniter sessions here

codeigniter session return-value

Like @Pattle said

$this->session->set_userdata('jezik', $data['jezik']);

Though I think he meant to pass in the array, like so:

$sessionData = array('jezik' => $data['jezik']);   $this->session->set_userdata($sessionData);

CodeHunter