On 12-06-02 1:15 AM, Kurtis Mullins wrote:
Have you tried b.haveone.all()?
Yes. Simplemindedly I wanted to try
B.haveone.all()
If I understand your suggestion, it would require iterating on instances
of B to find all instances of A mentioned in B.
that would be something like
for b in B.objects.all():
a = b.haveone.all()
...
which of course does work fine but may require visiting an instance of A
more than once.
What I'm looking for is to select all unique instances of A which appear
in B without iterating on B. Not all instances of A appearing in b (one
specific instance of B).
tia
- Tom
On Sat, Jun 2, 2012 at 12:36 AM, Thomas Lockhart
<tlockhart1...@gmail.com <mailto:tlockhart1...@gmail.com>> wrote:
I've got two models with one having a many-to-many relationship
with the other:
class A(models.Model):
name = models.CharField("name")
class B(models.Model):
haveone = models.ManyToManyField(A)
What is the idiom for getting all instances of A which are
referenced in B? I found this works:
A.objects.annotate(n=models.Count('b')).filter(n__gt=0)
But istm that there is probably a more concise and straightforward
way to accomplish this (and the solution is probably obvious but
it is escaping me). tia
- Tom
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