Doctrine2 get all the child records from adjacency list.

getchildren

    public function getSubOrgsForTranspnakl(Entity $topitem)
    {
        $childrenArray = array();
        $iterate = true;
        $listOfParents = array();
        $listOfParents = array_push($listOfParents, $topitem);

        while ($iterate){
            $q = $this
                ->createQueryBuilder('o')
                ->where('o.parent IN (:parentslist) ')
                ->setParameter('parentslist', $listOfParents)
                ->getQuery();
            $resultArray = $q->getResult();

            $listOfParents = $resulArray;
            $childrenArray = array_merge($childrenArray, $resultArray);

            if (count($resulArray) == 0) $iterate = false;
        }
        return $resultArray;
    }