How to merge two queries in Doctrine ORM - symfony

Question

I have table "weights", where I have numbers of weights for various cameras.
I want to sum last numbers for this cameras, therefore I am using two queries.
First query selects max ids for every camera and second selects numbers of weight for these ids.
public function maxIds($cameras)
{
return $this->createQueryBuilder("c")
->select('MAX(c.id) ')
->where('c.camera IN (:value)')
->setParameter('value', $cameras)
->groupBy('c.camera')
->getQuery()
->getArrayResult();
}
public function totalWeight($ids)
{
return $this->createQueryBuilder("c")
->select('SUM(c.number)')
->where('c.id IN (:value)')
->setParameter('value', $ids)
->getQuery()
->getOneOrNullResult();
}
These two queries work fine, but I would like to combine them into one query.
I am trying with this:
public function testWeight($cameras)
{
$qr = $this->createQueryBuilder('c')
->select('MAX(c.id) ')
->where('c.camera IN (:value)')
->setParameter('value', $cameras)
->groupBy('c.camera');
$qr->andWhere($qr->expr()->in('c.id',
$this->_em->createQueryBuilder()
->select('SUM(c.number)')
->getDQL()
));
return $qr->getQuery()
->getOneOrNullResult();
}
But I cannot success.
How can I solve this problem?

Answer 1

This is untested however what you are trying to do is a sub query which you can achieve in Doctrine. I also made some minor improvements to your query:
$subQuery = $this->getEntityManager()->createQueryBuilder();
$subQuery
->select('MAX(c2.id)')
->from(MyEntity::class, 'c2')
->where($subQuery->expr()->in('c2.camera', ':cameras'));
$queryBuilder = $this->createQueryBuilder('c')
$queryBuilder
->select('SUM(c.number)')
->where($queryBuilder->expr()->in('c.id', $subQuery->getDQL()))
->setParameter('cameras', $cameras);
->getQuery()
->getOneOrNullResult();