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from __future__ import unicode_literals
from django.db.models import Max
from django.test import TestCase, skipUnlessDBFeature
from django.test.utils import str_prefix
from .models import Celebrity, Fan, Staff, StaffTag, Tag
@skipUnlessDBFeature('can_distinct_on_fields')
@skipUnlessDBFeature('supports_nullable_unique_constraints')
class DistinctOnTests(TestCase):
def setUp(self):
t1 = Tag.objects.create(name='t1')
Tag.objects.create(name='t2', parent=t1)
t3 = Tag.objects.create(name='t3', parent=t1)
Tag.objects.create(name='t4', parent=t3)
Tag.objects.create(name='t5', parent=t3)
self.p1_o1 = Staff.objects.create(id=1, name="p1", organisation="o1")
self.p2_o1 = Staff.objects.create(id=2, name="p2", organisation="o1")
self.p3_o1 = Staff.objects.create(id=3, name="p3", organisation="o1")
self.p1_o2 = Staff.objects.create(id=4, name="p1", organisation="o2")
self.p1_o1.coworkers.add(self.p2_o1, self.p3_o1)
StaffTag.objects.create(staff=self.p1_o1, tag=t1)
StaffTag.objects.create(staff=self.p1_o1, tag=t1)
celeb1 = Celebrity.objects.create(name="c1")
celeb2 = Celebrity.objects.create(name="c2")
self.fan1 = Fan.objects.create(fan_of=celeb1)
self.fan2 = Fan.objects.create(fan_of=celeb1)
self.fan3 = Fan.objects.create(fan_of=celeb2)
def test_basic_distinct_on(self):
"""QuerySet.distinct('field', ...) works"""
# (qset, expected) tuples
qsets = (
(
Staff.objects.distinct().order_by('name'),
['<Staff: p1>', '<Staff: p1>', '<Staff: p2>', '<Staff: p3>'],
),
(
Staff.objects.distinct('name').order_by('name'),
['<Staff: p1>', '<Staff: p2>', '<Staff: p3>'],
),
(
Staff.objects.distinct('organisation').order_by('organisation', 'name'),
['<Staff: p1>', '<Staff: p1>'],
),
(
Staff.objects.distinct('name', 'organisation').order_by('name', 'organisation'),
['<Staff: p1>', '<Staff: p1>', '<Staff: p2>', '<Staff: p3>'],
),
(
Celebrity.objects.filter(fan__in=[self.fan1, self.fan2, self.fan3]).distinct('name').order_by('name'),
['<Celebrity: c1>', '<Celebrity: c2>'],
),
# Does combining querysets work?
(
(Celebrity.objects.filter(fan__in=[self.fan1, self.fan2]).
distinct('name').order_by('name') |
Celebrity.objects.filter(fan__in=[self.fan3]).
distinct('name').order_by('name')),
['<Celebrity: c1>', '<Celebrity: c2>'],
),
(
StaffTag.objects.distinct('staff', 'tag'),
['<StaffTag: t1 -> p1>'],
),
(
Tag.objects.order_by('parent__pk', 'pk').distinct('parent'),
['<Tag: t2>', '<Tag: t4>', '<Tag: t1>'],
),
(
StaffTag.objects.select_related('staff').distinct('staff__name').order_by('staff__name'),
['<StaffTag: t1 -> p1>'],
),
# Fetch the alphabetically first coworker for each worker
(
(Staff.objects.distinct('id').order_by('id', 'coworkers__name').
values_list('id', 'coworkers__name')),
[str_prefix("(1, %(_)s'p2')"), str_prefix("(2, %(_)s'p1')"),
str_prefix("(3, %(_)s'p1')"), "(4, None)"]
),
)
for qset, expected in qsets:
self.assertQuerysetEqual(qset, expected)
self.assertEqual(qset.count(), len(expected))
# Combining queries with different distinct_fields is not allowed.
base_qs = Celebrity.objects.all()
self.assertRaisesMessage(
AssertionError,
"Cannot combine queries with different distinct fields.",
lambda: (base_qs.distinct('id') & base_qs.distinct('name'))
)
# Test join unreffing
c1 = Celebrity.objects.distinct('greatest_fan__id', 'greatest_fan__fan_of')
self.assertIn('OUTER JOIN', str(c1.query))
c2 = c1.distinct('pk')
self.assertNotIn('OUTER JOIN', str(c2.query))
def test_distinct_not_implemented_checks(self):
# distinct + annotate not allowed
with self.assertRaises(NotImplementedError):
Celebrity.objects.annotate(Max('id')).distinct('id')[0]
with self.assertRaises(NotImplementedError):
Celebrity.objects.distinct('id').annotate(Max('id'))[0]
# However this check is done only when the query executes, so you
# can use distinct() to remove the fields before execution.
Celebrity.objects.distinct('id').annotate(Max('id')).distinct()[0]
# distinct + aggregate not allowed
with self.assertRaises(NotImplementedError):
Celebrity.objects.distinct('id').aggregate(Max('id'))
def test_distinct_on_in_ordered_subquery(self):
qs = Staff.objects.distinct('name').order_by('name', 'id')
qs = Staff.objects.filter(pk__in=qs).order_by('name')
self.assertQuerysetEqual(
qs, [self.p1_o1, self.p2_o1, self.p3_o1],
lambda x: x
)
qs = Staff.objects.distinct('name').order_by('name', '-id')
qs = Staff.objects.filter(pk__in=qs).order_by('name')
self.assertQuerysetEqual(
qs, [self.p1_o2, self.p2_o1, self.p3_o1],
lambda x: x
)
def test_distinct_on_get_ordering_preserved(self):
"""
Ordering shouldn't be cleared when distinct on fields are specified.
refs #25081
"""
staff = Staff.objects.distinct('name').order_by('name', '-organisation').get(name='p1')
self.assertEqual(staff.organisation, 'o2')
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