Symfony2 simple query: can't fetch an object, only array - symfony

Question

The following query in Symfony2.6 works with getArrayResult(); BUT doesn't work with getResult(); or getOneOrNullResult();. This means that I can't fetch an object but only an array.
If I use this query, all I get is a white/blank page (not even the symfony debug toolbar). Note that in my twig template I just do a {{ dump() }} of the query result.
The table structure is easy (it's a list of books read by the users):
id, user, book, status, vote, review
(user, book and status are foreign keys)
public function selectOneRecordBy2Ids($user_id, $book_id)
{
/* #var $qb QueryBuilder */
$qb = $this->createQueryBuilder('l');
$qb->select('l');
$qb = $qb->Where($qb->expr()->eq('l.user', ':first'));
$qb = $qb->andWhere($qb->expr()->eq('l.book', ':second'));
$qb = $qb->setParameters(array('first' => $user_id, 'second' => $book_id));
return $qb->getQuery()->getOneOrNullResult();
}

Answer 1

I've noticed a few bad practices here, so let me correct them:
public function selectOneRecordBy2Ids(User $user, Book $book)
{
/* #var $qb QueryBuilder */
$qb = $this->createQueryBuilder('l');
$qb
->andWhere($qb->expr()->eq('l.user', ':first'))
->andWhere($qb->expr()->eq('l.book', ':second'))
->setParameters(array('first' => $user, 'second' => $book));
return $qb->getQuery()->getResult();
}
Select is not necessary if you work only with one entity and you don't fetch any relations. QB returns $this so you can chain the method calls.
Try to use entities as parameters instead of primitive types (if it is possible). If not, then you have to use primitive types as primitives in QB. In this case you'll need a few joins:
->select('l')
->join('l.user', 'u')
->join('l.book', 'b')
->andWhere($qb->expr()->eq('u.id', ':first'))
->andWhere($qb->expr()->eq('b.id', ':second'))
->setParameters(array('first' => $user_id, 'second' => $book_id));
If you want to fetch only one record, then you may have to limit the results by setting the max results:
->setMaxResults(1)
I hope this helps and solves your original problem as well.

Answer 2

getOneOrNullResult() does not return the record, but tells you if any record in database is found, or not.
You might want to use getSingleResult()