Codeigniter中的会话变量不起作用

Question

Hi i have created a session in Codeigniter i have set the session variable in my model. But after setting the session variable value when i call session variable in my view through Controller the session variable value becomes null. Any help???

Update

This is my Model where i set my session variable

function login ($username, $password)

    {
        $this->db->where('username' , $username);
        $this->db->where('password', $password);

        $query = $this->db->get('users');

        if ($query->num_rows()>0)

        {
            foreach ($query->result() as $rows)
            {
                $data = array(

                    'user_name' => $rows->username,
                    'logged_in' => TRUE,
                    'validated' => true
                );
            }

                $this->session->set_userdata($data);
                //$user = $rows->username;
                //$this->session->set_userdata('user_name', $user);

                return true;
        }

        else

        {
            return false;
        }

    }

Here is my controller from where i redirect to the view

public function verification()

    {
        $username = $this->input->post('username');
        $password = $this->input->post('password');


        $result = $this->site_model->login($username, $password);


        //$result = $this->session->set_userdata('validated');

        if ($result)
        {
            //$this->admin();
            //$this->session->set_userdata('login_state', TRUE);

            redirect ('site/index');

        }
        else
        {

            redirect ('site/login');
            //$this->load->view('login');
        }
    }

i have called the session_start(); in controller under construct();

and this is how i access the session variable in my view

<?php if ($this->session->userdata('user_name') != "") { ?>

.....

Answer 1

use autoload applications/config/autoload.php, to add session liblary and remove session_start();

$autoload['libraries'] = array('session');

Model pass post data vithout varibles, you can do like that:

controller:

public function verification()
{
     $result = $this->site_model->login();

      if ($result){
          redirect ('site/index');
      } else {
          redirect ('site/login');
      }
}

Model:

public function login()
{
    $this->db->where('username' , $this->input->post('username'));
    $this->db->where('password', $this->input->post('password'));

    $query = $this->db->get('users');

    if ($query->num_rows()>0)

    {
        $res = $query->row_array();

        $data = array(
            'user_name' => $res['username'],
            'logged_in' => TRUE,
            'validated' => true
        );


        $this->session->set_userdata($data);
        return true;
    } else {
        return false;
    }
 }