private function getFieldData($field, Row $row, NodeInterface $node, $document, $templateKey, $webspaceKey, $locale)
    {
        if (isset($field['column'])) {
            // normal data from node property
            return $row->getValue($field['column']);
        } elseif (isset($field['extension'])) {
            // data from extension
            return $this->getExtensionData(
                $node,
                $field['extension'],
                $field['property'],
                $webspaceKey,
                $locale
            );
        } elseif (isset($field['property'])
            && (!isset($field['templateKey']) || $field['templateKey'] === $templateKey)
        ) {
            // not extension data but property of node
            return $this->getPropertyData($document, $field['property']);
        }

        return;
    }