public function ValidateData($sFormDataName = null)
    {
        if (is_null($sFormDataName)) {
            $sFormDataName = TdbDataExtranetUser::MSG_FORM_FIELD;
        }
        $bIsValid = parent::ValidateData($sFormDataName);
        $oMsgManager = TCMSMessageManager::GetInstance();

        // check postal code for country
        $bHasCountry = (array_key_exists('data_country_id', $this->sqlData) && !empty($this->sqlData['data_country_id']));
        $bHasPostalcode = (array_key_exists('postalcode', $this->sqlData) && !empty($this->sqlData['postalcode']));
        if ($bHasCountry && $bHasPostalcode) {
            $oCountry = TdbDataCountry::GetNewInstance();
            /** @var $oCountry TdbDataCountry */
            if ($oCountry->Load($this->sqlData['data_country_id'])) {
                if (!$oCountry->IsValidPostalcode($this->sqlData['postalcode'])) {
                    $oMsgManager->AddMessage($sFormDataName.'-postalcode', 'ERROR-USER-FIELD-INVALID-POSTALCODE');
                    $bIsValid = false;
                }
            }
        }

        return $bIsValid;
    }