doctrine query onetonmany / notIn with objects / symfony forms querybuilder - symfony

Question

I am using symfony 2 and doctrine to prefilter a form field type 'entity' with the help of a querybuilder.
My querybuilder should return all products which the user has not already added to a list.
All relations are bidirectionnal.
I have products linked to userIngredients (oneToMany) each linked to one user (manyToOne)
I have come with this so far but it's not working, I get products not added by other users.
return $this
->createQueryBuilder('p')
->leftJoin('p.userIngredients', 'i')
->where('i.user <> ?1')
->setParameter(1,$user);
1; Any clue on how to correct this ?
Alternatively, I could select the products I don't want and then reselect those who don't match but using an expression and NotIn seems to only work for strings
$products = $this
->createQueryBuilder('p')
->leftJoin('p.userIngredients', 'i')
->where('i.user = ?1')
->setParameter(1,$user)
->getQuery()
->getResult();
return $this
->createQueryBuilder('p')
->where($this->createQueryBuilder('p')->expr()->notIn('p', $products));
2; how could we correct this to make it work with objects ?
3; alternatively : is there a way to pass not a querybuilder but an array of results to symfony form builders ?

Answer 1

I got thinks thanks to Javad:
(slight modification, I'm using an array result, not dql):
$qb = $this->_em->createQueryBuilder();
$ids = $qb
->select('p.id')
->from('AppBundle:MarketPlace\Product','p','p.id')
->leftJoin('p.userIngredients', 'i')
->where('i.user = ?1')
->setParameter(1,$user)
->getQuery()
->getResult();
//I don't know why I couldn't directly get an array of ids otherwise... if you know how to do better directly from the query, I'm interested (getScalarResult does not make it)
$ids=array_keys($ids);
$result = $this
->createQueryBuilder('p')
->where($this->createQueryBuilder('p')->expr()->notIn('p.id', $ids));
return $result;