Doctrine 2, prevent getting unjoined entities - symfony

Question

given a user and his coupons, I want to get a user and all of his coupons:
foreach ($this->createQueryBuilder('x')->select('u, c')->where('x.email = ?0')->setParameter(0, $email)->leftJoin('u.coupons', 'c')->getQuery()->getResult() as $entity)
{
$entity->getCoupons();
}
this is very good until I forget to join the coupons:
foreach ($this->createQueryBuilder('x')->select('u')->where('x.email = ?0')->setParameter(0, $email)->getQuery()->getResult() as $entity)
{
$entity->getCoupons();
}
sadly this still works even though no coupons were joined. Here it does an other SELECT. In additional, this 2nd select will be wrong. Id rather want to get a exception or AT LEAST an empty array instead. Is there any workaround for this?

Answer 1

What you're experiencing is expected doctrine behavior.
When you select a User entity, Doctrine will get the record from the database. If you aren't explicitly joining the Coupon entity (or any other entities with relationship to User), Doctrine will create a Proxy object. Once you access this proxy object by calling $user->getCoupons(), Doctrine will fire a new query to the database to get the coupons for your User entity. This is called lazy-loading.
I'm not sure if there is a way to change this in the way you described.
What you can do is to create a method in your UserRepository called findUserAndCoupons($email) and have your query there. Whenever you need to find a user and his coupons, you could simply retrieve it in your controller using:
class MyController extends Controller {
public function myAction(){
$user = $this->getDoctrine()->getRepository('UserRepository')->findUserAndCoupons($email);
foreach($user->getCoupons() as $coupon) {
// ....
}
}
}
This way you won't need to remember the actual query and copy/paste it all over the place. :)