private function add_comment()
 {
     if (isset($_POST['comment'])) {
         $adv_id = isset($_POST['adventure2comment']) ? $_POST['adventure2comment'] : '';
         $content = isset($_POST['content']) ? $_POST['content'] : '';
         Model_adventure::add_comment($adv_id, $_SESSION["id"], $content);
         $this->display_adventure($adv_id);
     }
 }