Symfony2,创建querybuilder where子句,不为空或不为null

解决这个问题的另一个解决方案是:

public function findAllExcepcionesByItem($itemId) {
    $query = $this->createQueryBuilder('p')
        ->leftJoin('p.item', 'i')
        ->where("i.id = :actual")->setParameter("actual", $itemId)
        ->andWhere("p.excepcion != ''") // NOT EMPTY
        ->andWhere("p.excepcion IS NOT NULL") // NOT NULL
        ->getQuery();
    return $query->getResult();
}