Codeigniter handles the code for URL jump after user login verification

class MY_Controller extends CI_Controller
{
 public function __construct()
 {
 parent::__construct();
 /* Determine whether to log in and whether the current URL is auth/login*/
 if ( ! $this->tank_auth->is_logged_in()
 && ( $this->router->fetch_class() != 'auth' && $this->router->fetch_method() != 'login'))
 {
 $redirect = $this->uri->uri_string();

 if ( $_SERVER['QUERY_STRING'])
 {
 $redirect .= '?' . $_SERVER[ 'QUERY_STRING'];
 }
 /*Jump to the user login page, specify the URL to jump to after login*/
 redirect('auth/login?redirect='.$redirect);
 }
 }
}
? >

File: User.php

class User extends MY_Controller
{
 function login()
 {
 if ($this->tank_auth-> is_logged_in()) { // logged in
 redirect('/');
 } else {
 //other codes here...
 /*Determine whether there is redirect information */
 $data['redirect'] = isset($_GET['redirect']) ? $_GET['redirect'] : '/';
 if ($this-> ;form_validation->run()) { // validation ok
 if ($this->tank_auth->login(
 $this->form_validation->set_value('login'),
 $this-> ;form_validation->set_value('password'),
 $this->form_validation->set_value('remember'),
 $data['login_by_username'],
 $data['login_by_email'])) { / / success
 redirect($data['redirect']);
 } else {
 //error handling
 }
 }
 $this->load->view("login_form ")
 }
 }
/*
Note: In login_form, please note that the form address to submit the form is:

*/
}?>

In login_form, please note that the form address of the submitted form is: