function login_validation()
  {

       $this->load->library('form_validation');
       $this->form_validation->set_rules('username', 'Username', 'required');
       $this->form_validation->set_rules('password', 'Password', 'required');
       if($this->form_validation->run())
       {
            //true
            $username = $this->input->post('username');
            $password = $this->input->post('password');
            //model function
            $this->load->model('main_model');
            if($this->main_model->can_login($username, $password))
            {
                 $session_data = array(
                      'username'     =>     $username
                 );
                 $this->session->set_userdata($session_data);
                 redirect('login/enter');
            }
            else
            {
                 $this->session->set_flashdata('error', 'Invalid Username or Password');
                 redirect('login/index');
            }
       }
       else
       {
            //false
            $this->index();
       }
  }
public function enter(){
       if($this->session->userdata('username') != '')
       {
            $this->load->view('includes/dashlink');
            $this->load->view('includes/dashheader');
            $this->load->view('index');
            $this->load->view('includes/dashfooter');


       }
       else
       {
            redirect(base_url() . 'login/index');
       }
  }
public function logout() {

$this->session->sess_destroy();
$data['message_display'] = 'Successfully Logout';
$this->load->view('login', $data);

    }

function __construct() {
            parent::__construct();
$this->load->library('session');
    if(!$this->session->userdata(' $session_data')){
    redirect(login);
    }
        }