django/tests/null_fk/tests.py

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from __future__ import unicode_literals
from django.db.models import Q
from django.test import TestCase
from .models import (SystemDetails, Item, PropertyValue, SystemInfo, Forum,
Post, Comment)
class NullFkTests(TestCase):
def test_null_fk(self):
d = SystemDetails.objects.create(details='First details')
s = SystemInfo.objects.create(system_name='First forum', system_details=d)
f = Forum.objects.create(system_info=s, forum_name='First forum')
p = Post.objects.create(forum=f, title='First Post')
c1 = Comment.objects.create(post=p, comment_text='My first comment')
c2 = Comment.objects.create(comment_text='My second comment')
# Starting from comment, make sure that a .select_related(...) with a specified
# set of fields will properly LEFT JOIN multiple levels of NULLs (and the things
# that come after the NULLs, or else data that should exist won't). Regression
# test for #7369.
c = Comment.objects.select_related().get(id=c1.id)
self.assertEqual(c.post, p)
self.assertEqual(Comment.objects.select_related().get(id=c2.id).post, None)
self.assertQuerysetEqual(
Comment.objects.select_related('post__forum__system_info').all(),
[
(c1.id, 'My first comment', '<Post: First Post>'),
(c2.id, 'My second comment', 'None')
],
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transform=lambda c: (c.id, c.comment_text, repr(c.post))
)
# Regression test for #7530, #7716.
self.assertTrue(Comment.objects.select_related('post').filter(post__isnull=True)[0].post is None)
self.assertQuerysetEqual(
Comment.objects.select_related('post__forum__system_info__system_details'),
[
(c1.id, 'My first comment', '<Post: First Post>'),
(c2.id, 'My second comment', 'None')
],
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transform=lambda c: (c.id, c.comment_text, repr(c.post))
)
def test_combine_isnull(self):
item = Item.objects.create(title='Some Item')
pv = PropertyValue.objects.create(label='Some Value')
item.props.create(key='a', value=pv)
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item.props.create(key='b') # value=NULL
q1 = Q(props__key='a', props__value=pv)
q2 = Q(props__key='b', props__value__isnull=True)
# Each of these individually should return the item.
self.assertEqual(Item.objects.get(q1), item)
self.assertEqual(Item.objects.get(q2), item)
# Logically, qs1 and qs2, and qs3 and qs4 should be the same.
qs1 = Item.objects.filter(q1) & Item.objects.filter(q2)
qs2 = Item.objects.filter(q2) & Item.objects.filter(q1)
qs3 = Item.objects.filter(q1) | Item.objects.filter(q2)
qs4 = Item.objects.filter(q2) | Item.objects.filter(q1)
# Regression test for #15823.
self.assertEqual(list(qs1), list(qs2))
self.assertEqual(list(qs3), list(qs4))