django/tests/null_queries/tests.py

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from django.core.exceptions import FieldError
from django.test import TestCase
from .models import Choice, Inner, OuterA, OuterB, Poll
class NullQueriesTests(TestCase):
def test_none_as_null(self):
"""
Regression test for the use of None as a query value.
None is interpreted as an SQL NULL, but only in __exact and __iexact
queries.
Set up some initial polls and choices
"""
p1 = Poll(question='Why?')
p1.save()
c1 = Choice(poll=p1, choice='Because.')
c1.save()
c2 = Choice(poll=p1, choice='Why Not?')
c2.save()
# Exact query with value None returns nothing ("is NULL" in sql,
# but every 'id' field has a value).
self.assertSequenceEqual(Choice.objects.filter(choice__exact=None), [])
# The same behavior for iexact query.
self.assertSequenceEqual(Choice.objects.filter(choice__iexact=None), [])
# Excluding the previous result returns everything.
self.assertSequenceEqual(Choice.objects.exclude(choice=None).order_by('id'), [c1, c2])
# Valid query, but fails because foo isn't a keyword
with self.assertRaises(FieldError):
Choice.objects.filter(foo__exact=None)
# Can't use None on anything other than __exact and __iexact
with self.assertRaises(ValueError):
Choice.objects.filter(id__gt=None)
# Related managers use __exact=None implicitly if the object hasn't been saved.
p2 = Poll(question="How?")
self.assertEqual(repr(p2.choice_set.all()), '<QuerySet []>')
def test_reverse_relations(self):
"""
Querying across reverse relations and then another relation should
insert outer joins correctly so as not to exclude results.
"""
obj = OuterA.objects.create()
self.assertSequenceEqual(OuterA.objects.filter(inner__third=None), [obj])
self.assertSequenceEqual(OuterA.objects.filter(inner__third__data=None), [obj])
inner = Inner.objects.create(first=obj)
self.assertSequenceEqual(Inner.objects.filter(first__inner__third=None), [inner])
# Ticket #13815: check if <reverse>_isnull=False does not produce
# faulty empty lists
outerb = OuterB.objects.create(data='reverse')
self.assertSequenceEqual(OuterB.objects.filter(inner__isnull=False), [])
Inner.objects.create(first=obj)
self.assertSequenceEqual(OuterB.objects.exclude(inner__isnull=False), [outerb])