public function getParentPageIds()
    {
        $rootLineParentPageIds = [];
        if (empty($this->rootLineArray)) {
            // no rootline given
            return $rootLineParentPageIds;
        }

        foreach ($this->rootLineArray as $pageRecord) {
            $rootLineParentPageIds[] = $pageRecord['uid'];
            if (Site::isRootPage($pageRecord)) {
                break;
            }
        }

        return $rootLineParentPageIds;
    }