Symfony createquery with union - sql

Question

I need to execute the next query with symfony :
$qb = $this->_em;
$query = $qb->createQuery(
'SELECT f1.friend1
FROM AppBundle:Friend f1
WHERE f1.friend2 = ?1
UNION
SELECT f2.friend2
FROM AppBundle:Friend f2
WHERE f2.friend1 = ?2
'
)->setParameters(array(1 => $user_id, 2 => $user_id));
When i execute this $query, i have this error : Expected end of string, got 'UNION'.
How can i do ?
Edit for my new code :
$rsm = new \Doctrine\ORM\Query\ResultSetMapping();
$rsm->addEntityResult('Project\MyBundle\Entity\Friend', 'f');
$rsm->addFieldResult('f', 'friend1', 'friend1');
$rsm->addFieldResult('f', 'friend2', 'friend2');
$rsm->addFieldResult('f', 'id', 'id');
$rsm->addFieldResult('f', 'state', 'state');
$sql = "SELECT f1.friend1 AS friend
FROM friend f1
WHERE f1.friend2 = ?
UNION
SELECT f2.friend2 AS friend
FROM friend f2
WHERE f2.friend1 = ?";
$result = $this->_em->createNativeQuery($sql, $rsm)
->setParameter(1, $user_id)
->setParameter(2, $user_id)
->getResult();
return $result;
This is my new query. I have test this query directly on phpmyadmin, and i have a return. But with this code, i have empty in $result

Answer 1

UNION is not supported in doctrine instead you can use Doctrine\ORM\Query\ResultSetMapping; this will map your resultset to the entity which you defined to use by the native query like $rsm->addEntityResult('Namespace\yourBundle\Entity\Friend', 'f');
$rsm = new \Doctrine\ORM\Query\ResultSetMapping();
$rsm->addEntityResult('Namespace\yourBundle\Entity\Friend', 'f');
$rsm->addFieldResult('f', 'friend', 'friend1');
$sql = "SELECT f1.friend1 AS friend
FROM friend_table f1
WHERE f1.friend2 = ?
UNION
SELECT f2.friend2 AS friend
FROM friend_table f2
WHERE f2.friend1 = ?";
$result = $DM->createNativeQuery($sql, $rsm)
->setParameter(1, $user_id)
->setParameter(2,$user_id)
->getResult();
Edit from comments
Not advisable solution due to lack of information why using union but the answer for question in comments below you can do so to map fields,but remember this will give you the duplicates
$rsm = new \Doctrine\ORM\Query\ResultSetMapping();
$rsm->addEntityResult('Project\MyBundle\Entity\Friend', 'f');
$rsm->addFieldResult('f', 'friend1', 'friend1');
$rsm->addFieldResult('f', 'friend2', 'friend2');
$rsm->addFieldResult('f', 'id', 'id');
$rsm->addFieldResult('f', 'state', 'state');
$sql = "SELECT f1.id,f1.friend1 AS friend,f1.friend1,f1.friend2 ,f1.state
FROM friend f1
WHERE f1.friend2 = ?
UNION
SELECT f2.id,f2.friend2 AS friend,f2.friend1,f2.friend2 ,f2.state
FROM friend f2
WHERE f2.friend1 = ?";
$result = $this->_em->createNativeQuery($sql, $rsm)
->setParameter(1, $user_id)
->setParameter(2, $user_id)
->getResult();
Edit 2 i just want an array with one field "friend", with friend1 in one case, and friend2 in another
For the above you asked you can run two queries using your entity
$DM = $this->getDoctrine()->getEntityManager();
$result1=$DM->getRepository('Namespace\yourBundle\Entity\Friend')
->findBy(array('friend2'=>$user_id));
$result2=$DM->getRepository('Namespace\yourBundle\Entity\Friend')
->findBy(array('friend1'=>$user_id));