protected function GetVariantType($aRow)
    {
        $sKey = 'oVariantType_'.$aRow['shop_variant_set_id'];
        $oVariantType = &$this->GetFromInternalCache($sKey);
        if (null === $oVariantType) {
            $oVariantType = TdbShopVariantType::GetNewInstance();
            if (!empty($aRow['shop_variant_set_id'])) {
                if (!$oVariantType->LoadFromFields(array('identifier' => $this->sVariantTypeIdentifier, 'shop_variant_set_id' => $aRow['shop_variant_set_id']))) {
                    $oVariantType = false;
                }
            } else {
                $oVariantType = false;
            }
            $this->SetInternalCache($sKey, $oVariantType);
        }

        return $oVariantType;
    }