Symfony queryBuilder subquery

query_builder_sub_query.php

    /**
     * @param User $user
     * @param int $limit
     * @param int $offset
     * @return User[]
     */
    public function getUserFollowers(User $user, $limit = 20, $offset = 0)
    {
        $_followersIds = $this->getEntityManager()
            ->createQueryBuilder()
            ->select('IDENTITY(r.followeduser)')
            ->from($this->getEntityName(), 'r')
            ->where('r.followeeuser = :user')
            ->andWhere('r.followeduser !=:user')
            ->setParameter('user', $user)
            ->orderBy('r.id', 'DESC')
            ->setFirstResult($offset)
            ->setMaxResults($limit)
            ->getQuery()
            ->getResult();

        $_usersQb = $this->getEntityManager()->createQueryBuilder();
        $_usersQb
            ->select('u')
            ->from('UserBundle:User', 'u')
            ->where('u.id IN (:followersIds)')
            ->setParameter('followersIds', array_values($_followersIds));

        return $_usersQb->getQuery()->getResult();
    }