protected function _saveSortingFieldValuesOnLoad()
    {
        $aSortingFields = \OxidEsales\Eshop\Core\Registry::getConfig()->getConfigParam('aSortCols');
        $aSortingFields = !empty($aSortingFields) ? (array) $aSortingFields : [];

        foreach ($aSortingFields as $sField) {
            $sFullField = $this->_getFieldLongName($sField);
            $this->_aSortingFieldsOnLoad[$sFullField] = $this->$sFullField->value;
        }
    }