private function getParam($key)
    {
        if (!$this->getParams) {
            $this->getParams = filter_input(INPUT_GET, self::UKEY1_GET_PARAM, FILTER_DEFAULT, FILTER_REQUIRE_ARRAY);
        }
        
        if (isset($this->getParams[$key]) && $this->getParams[$key] && (is_string($this->getParams[$key]) || is_numeric($this->getParams[$key]))) {
            return $this->getParams[$key];
        } else {
            return "";
        }
    }