Question

I am use following code to retrieve the session variable in routes.php

if($this->db_session->userdata('request_url')!="")
{
$route['user/(:any)'] = "search_user_name/redirect_url/".$_SESSION['request_url'];
$this->db_session->unset_userdata('request_url');
}
else {
    $route['user/(:any)'] = "search_user_name/index/$1";
}

the session variable would be set into template/header.php

$this->db_session->set_userdata('request_url', $_SERVER["SERVER_NAME"].$_SERVER["REQUEST_URI"]);

Answer 1

You can not use db_session in routes.php because routes.php is parsed before db_session is loaded.
Maybe you should create a base controller and redirect from the constructor of the base controller.