Doctrine 2 delete with query builder - php

Question

I have two Entities with relation OneToMany, Project and Services. Now i want to remove all the services by project_id.
First attempt:
$qb = $em->createQueryBuilder();
$qb->delete('Services','s');
$qb->andWhere($qb->expr()->eq('s.project_id', ':id'));
$qb->setParameter(':id',$project->getId());
This attempt fails with the Exception Entity Service does not have property project_id. And it's true, that property does not exists, it's only in database table as foreign key.
Second attempt:
$qb = $em->createQueryBuilder();
$qb->delete('Services','s')->innerJoin('s.project','p');
$qb->andWhere($qb->expr()->eq('p.id', ':id'));
$qb->setParameter(':id',$project->getId());
This one generetate a non valid DQL query too.
Any ideas and examples will be welcome.

Answer 1

You're working with DQL, not SQL, so don't reference the IDs in your condition, reference the object instead.
So your first example would be altered to:
$qb = $em->createQueryBuilder();
$qb->delete('Services', 's');
$qb->where('s.project = :project');
$qb->setParameter('project', $project);

Answer 2

If you really can't get project object and you have to handle only with id you can use this.
Citation from doctrine documentation:
There are two possibilities for bulk deletes with Doctrine. You can either issue a single DQL DELETE query or you can iterate over results removing them one at a time. (Below I paste only first solution)
DQL Query
The by far most efficient way for bulk deletes is to use a DQL DELETE query.
Example that worked in my project
$q = $em->createQuery('delete from AcmeMyTestBundle:TemplateBlock tb where tb.template = '.intval($templateId));
$numDeleted = $q->execute();
In entity TemplateBlock I have property called template which is mapped to template_id in db.
But I agree that highly preferred way of doing it is using objects.