php - Codeigniter - sessions not working through controller and view -

i'm trying make login using sessions in codeigniter @ time username , password match, can't it. i'm doing this:

controller:

public function __construct()     {         parent::__construct();         $this->load->model('main_select');         $this->load->helper('url');         $this->load->library('session');      }      ...code when username , password match: if($pass === $user){         $this->session->set_userdata(array(                                     'user_id' => $login['id_user'],                             ));//we create session 'user_id' } 

here supposed created session called 'user_id' in view doesn't work, have this:

if( !$this->session->userdata('id_user') ){ //see content //first content }else{ //see other //second content } 

but see same content('second content').

trying destroy (but not working):

public function logout()     {         //session_unset();          // destroy session          //session_destroy();         $this->session->unset_userdata('id_user');                header("location: ".base_url() );     } 

what doing wrong? thanks

edit1:

$password = md5( $this->input->post('inputpassword') );  $login =  $this->login_select->get_username($username);  //si no coincide if( $login['password'] !== $password ) {} 

note : use database handle user logins. (code related database login check)

in database create table user , add 2 fields.

1. username
2. password

add user logins it

then in code

public function __construct()     {         parent::__construct();         $this->load->model('main_select');         $this->load->helper('url');         $this->load->library('session');      }  // logging public function loging() {     $user = mysql_real_escape_string($_post['username']);     $pass = md5(mysql_real_escape_string($_post['password']));      $validate = $this->main_select->validate_user($user,$pass);      if(empty($validate) || $validate>1)     {         //not valid user         //redirect login page         $this->load->view('loging');     }     else     {         //valid user         //set session          $array = array('user_id' => '$user');         $this->session->set_userdata();         //redirect normal page         $this->load->view('home_page');     } }  //logout public function logout() {      $result= $this->session->sess_destroy();       if ((isset($result)))      {         header("location: ".base_url() );     }         else     {      }   } 

in model

public function validate_user($user,$pass) {     $query = $this->db->query("select * user username= '$user' , password='$pass'");     $result = $query->result_array();     $count = count($result);     return $count; }