Session Library another Error

[eluser]pistolPete[/eluser]
You need to use the function set_userdata()!
Please see the user guide:

Adding Custom Session Data
...
To add your data to the session array involves passing an array containing your new data to this function:

Code:

$this->session->set_userdata($array);

Code:

if($this->session->userdata('hash_string'))
{
    $this->session->set_userdata(array('last_hash_string' =>   $this->session->userdata('hash_string')));
}
$this->session->set_userdata(array('hash_string' => random_string('alnum', 6)));