Doctrine DQL Delete from relation table

问题

Using Doctrine 2 and Symfony 2.0.

I have two Doctrine entities (let's suppose EntityA and EntityB).

I have a ManyToMany relation between them. So a EntityA_EntityB table has been created in database.

Using DQL or QueryBuilder, how can I delete from that relation table EntityA_EntityB?

Docrtine offers something like this to perform something similar:

->delete()
 ->from('EntityA a')
 ->where('a.id', '?', $id);

But I don't really get how to perform the deletion of row from the relation table.

回答1:

$em = ...; // instance of `EntityManager`

// fetch both objects if ID is known
$a = $em->getRepository("YourProjectNamespace:EntityA")->find($id_of_A);
$b = $em->getRepository("YourProjectNamespace:EntityB")->find($id_of_B);

// suppose you have `EntityA::getObjectsOfTypeB` which retrieves all of linked objects of type `EntityB`.
// This method return instacne of ArrayCollection
$a->getObjectsOfTypeB()->removeElement($b);
$em->flush();

Something like this?

Basically, you need to remove related object from collection rather than delete relation itself. you want to remove relation directly you can always use pure SQL, but in DQL that is not possible.

Raw DELETE SQL statement via DBAL Connection object

$conn = $this->getDoctrine()->getManager()->getConnection();
$stmt = $conn->prepare("DELETE FROM EntityAEntityB WHERE id_b IN (:ids_of_b)");
$stmt->bindParam('ids_of_b', $to_delete_ids); // BEWARE: this array has to have at least one element
$stmt->executeUpdate();

来源：https://stackoverflow.com/questions/20035069/doctrine-dql-delete-from-relation-table