FileDiskProperty::getObjectId

static function getObjectId($attachedId)
{
	$attachedId = (int)$attachedId;
	$attachedModel = AttachedObject::loadById($attachedId, array('OBJECT'));

	if(!$attachedModel)
	{
		return null;
	}
	$objectId = $attachedModel->getObjectId();
	if(!$objectId)
	{
		return null;
	}

	return $objectId;
}