Django - filtering by "certain value or None"

Question

I have a field in an data object that can be either null or set to some integer. I want, given an integer, to filter all the objects with that integer value OR none:

MyElements.objects.all().filter(value__in=[myInt, None])

However, this line does not work for elements with null value. More precisely:

MyElements.objects.all().filter(value__in=[None])

returns nothing. whereas

MyElements.objects.all().filter(value = None)

returns the null-valued elements.

How can I rewrite the original query (which involves myInt) correctly?

score 18 · Accepted Answer · answered Dec 10 '13 at 08:36

18

You can use Q values which allow you to combine multiple clauses in Django querysets.

Your query set would be something like:

from django.db.models import Q
MyElements.objects.all().filter(Q(value=None) | Q(value=myInt))

answered Dec 10 '13 at 08:36

Kevin Stone

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29

Thanks to both of you, I didn't know about Q values until now. – Gadi A Dec 10 '13 at 08:41
Is there any explanation why `in` lookup not work for `None` in an iterable? – hashlash Jun 18 '19 at 17:21

score 7 · Answer 2 · answered Dec 10 '13 at 08:35

7

You can try OR statement:

from django.db.models import Q
MyElements.objects.filter(Q(value__isnull=True) | Q(value=myInt))

django documentation

answered Dec 10 '13 at 08:35

Lukasz Koziara

4,274
5
32
43

Django - filtering by "certain value or None"

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