Pimcore\Model\Object\ClassDefinition\Data\Multihref::getDataForQueryResource PHP Method

    public function getDataForQueryResource($data, $object = null, $params = [])
    {
        //return null when data is not set
        if (!$data) {
            return null;
        }
        $d = [];
        if (is_array($data) && count($data) > 0) {
            foreach ($data as $element) {
                if ($element instanceof Element\ElementInterface) {
                    $elementType = Element\Service::getElementType($element);
                    $d[] = $elementType . "|" . $element->getId();
                }
            }
            return "," . implode(",", $d) . ",";
        } elseif (is_array($data) && count($data) === 0) {
            return "";
        } else {
            throw new \Exception("invalid data passed to getDataForQueryResource - must be array");
        }
    }