Codeigniter處理使用者登入驗證後URL跳轉

class MY_Controller extends CI_Controller
{
    public function __construct()
    {
        parent::__construct();
        /*判斷是否登入，判斷當前URL是否是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 .= `?` . $_SERVER[`QUERY_STRING`];
            }
            /*跳轉到使用者登陸頁面，指定Login後跳轉的URL*/
            redirect(`auth/login?redirect=`.$redirect);
        }    
    }
}

class User extends MY_Controller 
{
    function login()
    {

        if ($this->tank_auth->is_logged_in()) {                                    // logged in
            redirect(`/`);

        } else {
            //other codes here......
            /*判斷是否有redirect資訊*/
            $data[`redirect`] = isset($_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
                }
            }
            $this->load->view("login_form")
        }
    }
/*
Note: 在login_form中需要注意，提交表單的form地址：
<?php echo form_open(site_url("/auth/login?redirect=".$redirect)); ?>
*/
}

在login_form中需要注意，提交表單的form地址：

<?php echo form_open(site_url("/auth/login?redirect=".$redirect)); ?>