CODEWITHSUNDEEP
pythondjango
user2061057
user2061057

Reputation: 1022

Django QuerySet.exclude(): Why are all excluded?

I have a situation like this:

ids = [None, None, None]
foo = Foo.objects.filter(common=True).exclude(id__in=ids)

This seems to exclude all always.

Why is id of id__in threated as None in this case? pk__in didn't work either. I expect it to not exclude anything as all objects have valid id's.

foo = Foo.objects.filter(common=True)

Returns all objects like expected.

Upvotes: 6

Views: 3012

Answers (1)

Alasdair
Alasdair

Reputation: 308829

Your queryset will generate SQL similar to select * from foo where NOT (id in (NULL));

In SQL both x in (NULL) and NOT (x in (NULL)) evaluate to null, so the query returns no rows. See this question for more info.

The solution, as @wim pointed out in the comments, is to filter out the None values from the list:

foo = Foo.objects.filter(common=True).exclude(id__in=[x for x in ids if x is not None])

Upvotes: 7

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