Code Igniter session declaration - codeigniter

Question

I am new to CodeIgniter framework. I am using 2.1.4 version. I designed a simple login form, with a javascript validation, and the home page of a site. Can you please help me to understand how to declare session , and how to destroy the session on clicking signout link.
controller file of login page ( to load the view page login.php ):-
class Login extends CI_Controller {
function __construct() {
parent::__construct();
$this->load->helper('url');
}
function index(){
$this->load->view('login');
}
function success() {
redirect ('home');
}
}
The controller file home.php for the view home.php
class Home extends CI_Controller {
// local constructor will be overriding the one in the parent controller class
// for using a constructor in any of my Controllers
function __construct() {
parent::__construct();
}
public function index()
{
$this->load->view('home');
}
}
I have designed the view page home.php, and gave the signout link:-
<div class="logout">Signout</div>
For initializing the session, i need to know, what all constructor changes/ config changes need, and the method of session destoy.

Answer 1

To start session library, Go to application/config/config.php and change the below line:
$autoload['libraries'] = array('session');
It would be better if you start your session in the autoload.php. To destroy session you would use :
$this->session->sess_destroy();
To set session :
$newdata = array(
'username' => 'johndoe',
'email' => 'johndoe#some-site.com',
'logged_in' => TRUE
);
$this->session->set_userdata($newdata);

Answer 2

here is an controller... first of all u need to declare a session so that you have two choice to declare one is Go to application/config/config.php change the code as
$autoload['libraries'] = array('session');
and follow this following method (controller)
class Login extends CI_Controller{
function __construct(){
parent::__construct();
$this->load->library('session');
}
function index(){
$this->load->view('login');
}
function success() {
$user=$this->input->post('user');
$psw=$this->input->post('pswd');
$this->load->model('validation');
$result=$this->validation->useraccess($user,$psw);
if($result)
{
$this->session->set_userdata('username', $user); //setting session
redirect ('home');
}
else
{
$this->index();
}
}
function logout()
{
$this->session->unset_userdata('username');
redirect('login','refresh');
}
}
this is model where validation done
Class Validation extends CI_Model{
function __construct(){
parent::__construct();
}
function useraccess($user,$pswd)
{
$query = $this->db->query("select * from user where username='$user' AND password='$pswd'");
foreach ($query->result_array() as $row)
{
if($row['username']==$user AND $row['password']==$pswd)
{
return true;
}
else
{
return false;
}
}
}
}
here is a view
login page
create 2 text box and 1 submit button and declare form action as
localhost/index.php/login/success
for logut
localhost/index.php/login/logout