Hi all,
I'm seeing some funny behavior when using select_related to try to speed up
my code, and I'm wondering if I'm just misunderstanding something.
The basics of my code:
class A(models.Model):
# some stuff
class B(models.Model):
a = models.ForeignKey('A')
c = models.ForeignKey('C')
d = models.ForeignKey('D')
e = models.ForeignKey('E')
# some stuff
a = A.objects.get(pk=some_id)
b_set = a.b_set.all()
When I do this, b_set has about 8 things in it, and I can get to c, d, e,
and other things just fine. But, presumably, accessing b.c, b.d, and b.e
are each database calls, and I would like to avoid those if I can.
So to get rid of those database calls and just get all of the related fields
in a single query, I do this:
a = A.objects.get(pk=some_id)
b_set = a.b_set.select_related().all() # recommended in the Django
documentation for some queries
And b_set comes up empty, for some reason that I can't explain. The only
difference between the two blocks of code is the select_related() call, and
it changes the result by not giving me anything back. Any ideas?
Thanks,
Matt
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