public function clearHistoryAction()
 {
     if (!Zend_Auth::getInstance()->hasIdentity()) {
         return $this->_redirect('/');
     }
     $user = new Zend_Session_Namespace('user');
     $user_id = $user->user['id'];
     $where = array('condition' => 'user_id = ?', 'param' => $user_id);
     if ($this->_store_url) {
         $history_url_mapper = new Application_Model_HistoryUrlMapper();
         $history_url_mapper->deleteWhere($where);
     } else {
         $history_mapper = new Application_Model_HistoryMapper();
         $history_mapper->deleteWhere($where);
     }
     return $this->_redirect('/history');
 }