Hi,
I have the following structure:
class A(models.Model):
date = DateField(nullable=True)
...
class B(models.Model):
a = ForeignKey(A)
a_date_is_null_at_creation = BooleanField()
...
I select the following data this way: (an O(n) operation for n A)
a = A.objects.get(id=1)
relevant_b = a.b_set.get(is_start=(a.date==None))
, which is similar to
A.objects.get(id=1).prefetch_related(b_set)
, and constructs 2 queries.
Can I construct a queryset which selects the relevant B row inline with the
A query, such that only one query is executed?
there is always only one result for B.is_start == (B.a.date == Null)
Thanks in advance,
-M Meent
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