Question

Consider the model schema:

class A(models.Model):
  id = models.IntegerField(...)
  ...

class B(models.Model):
  parent = models.OneToOneField(A, primary_key=True)

And further assume that there are more rows of A than B (e.g. not all As have details). How would I generate a query that gives me only As which have associated Bs?

I’ve tried A.objects.filter(b__isnull=False) which doesn’t seem to work, it still returns all rows in A.

Answer 1

I just tried this, and it works for me:

A.objects.exclude(b=None)

or, a somewhat hackier version that relies on the (usually) integer non negative nature of primary keys

A.objects.filter(b__id__gte=0)

Now, I have a related_name, so if those don’t work for you, try adding related_name.

class Profile(models.Model):
    user   = models.OneToOneField(User, related_name='profile')