/**
  * @access protected
  * @param string $key
  * @param string $fieldName
  */
 protected function _setStringValueToBuffer($key, $fieldName)
 {
     if ($this->_currentContainer->isValueSet($key)) {
         $value = $this->_currentContainer->getValue($key);
         $this->_buffer[] = $fieldName . ' = ' . $this->_escapeString($value);
     }
 }