/**
  * List course descriptions.
  * 
  * @param array messages 
  */
 public function index()
 {
     $course = Request::get_course_key();
     $user_id = api_get_user_id();
     $column = Request::get_sort_column();
     $direction = Request::get_sort_direction();
     $order_by = $column ? "{$column} {$direction}" : '';
     $repo = Notebook::repository();
     $items = $repo->find_by_course_and_user($course, $user_id, $order_by);
     $data = (object) array();
     $data->items = $items;
     $data->sort = $sort;
     $data->sort_direction = $direction;
     $data->sort_column = $column;
     $this->render('index', $data);
 }