function check_favorite()
 {
     $isin = isset($_REQUEST['isin']) ? $_REQUEST['isin'] : $_REQUEST['id'];
     if ($isin) {
         $conn = $this->get_connection();
         $favorite_factory = new Favorite();
         $favorites = $favorite_factory->find_all(array('where_clause' => "`utente` = '{$conn->escape($_COOKIE['username'])}' " . "AND `isin` = '{$conn->escape($isin)}'"));
         $this->is_favorite = count($favorites) > 0;
         $this->favorite = $favorites[0];
     }
 }