from django.db import connection from django.db.models import CharField, Max from django.db.models.functions import Lower from django.test import TestCase, skipUnlessDBFeature from django.test.utils import register_lookup from .models import Celebrity, Fan, Staff, StaffTag, Tag @skipUnlessDBFeature('can_distinct_on_fields') @skipUnlessDBFeature('supports_nullable_unique_constraints') class DistinctOnTests(TestCase): @classmethod def setUpTestData(cls): cls.t1 = Tag.objects.create(name='t1') cls.t2 = Tag.objects.create(name='t2', parent=cls.t1) cls.t3 = Tag.objects.create(name='t3', parent=cls.t1) cls.t4 = Tag.objects.create(name='t4', parent=cls.t3) cls.t5 = Tag.objects.create(name='t5', parent=cls.t3) cls.p1_o1 = Staff.objects.create(id=1, name="p1", organisation="o1") cls.p2_o1 = Staff.objects.create(id=2, name="p2", organisation="o1") cls.p3_o1 = Staff.objects.create(id=3, name="p3", organisation="o1") cls.p1_o2 = Staff.objects.create(id=4, name="p1", organisation="o2") cls.p1_o1.coworkers.add(cls.p2_o1, cls.p3_o1) cls.st1 = StaffTag.objects.create(staff=cls.p1_o1, tag=cls.t1) StaffTag.objects.create(staff=cls.p1_o1, tag=cls.t1) cls.celeb1 = Celebrity.objects.create(name="c1") cls.celeb2 = Celebrity.objects.create(name="c2") cls.fan1 = Fan.objects.create(fan_of=cls.celeb1) cls.fan2 = Fan.objects.create(fan_of=cls.celeb1) cls.fan3 = Fan.objects.create(fan_of=cls.celeb2) def test_basic_distinct_on(self): """QuerySet.distinct('field', ...) works""" # (qset, expected) tuples qsets = ( ( Staff.objects.distinct().order_by('name'), [self.p1_o1, self.p1_o2, self.p2_o1, self.p3_o1], ), ( Staff.objects.distinct('name').order_by('name'), [self.p1_o1, self.p2_o1, self.p3_o1], ), ( Staff.objects.distinct('organisation').order_by('organisation', 'name'), [self.p1_o1, self.p1_o2], ), ( Staff.objects.distinct('name', 'organisation').order_by('name', 'organisation'), [self.p1_o1, self.p1_o2, self.p2_o1, self.p3_o1], ), ( Celebrity.objects.filter(fan__in=[self.fan1, self.fan2, self.fan3]).distinct('name').order_by('name'), [self.celeb1, self.celeb2], ), # 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')), [self.celeb1, self.celeb2], ), (StaffTag.objects.distinct('staff', 'tag'), [self.st1]), ( Tag.objects.order_by('parent__pk', 'pk').distinct('parent'), [self.t2, self.t4, self.t1] if connection.features.nulls_order_largest else [self.t1, self.t2, self.t4], ), ( StaffTag.objects.select_related('staff').distinct('staff__name').order_by('staff__name'), [self.st1], ), # Fetch the alphabetically first coworker for each worker ( (Staff.objects.distinct('id').order_by('id', 'coworkers__name'). values_list('id', 'coworkers__name')), [(1, 'p2'), (2, 'p1'), (3, 'p1'), (4, None)], ), ) for qset, expected in qsets: self.assertSequenceEqual(qset, expected) self.assertEqual(qset.count(), len(expected)) # Combining queries with different distinct_fields is not allowed. base_qs = Celebrity.objects.all() with self.assertRaisesMessage(AssertionError, "Cannot combine queries with different distinct fields."): 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_transform(self): new_name = self.t1.name.upper() self.assertNotEqual(self.t1.name, new_name) Tag.objects.create(name=new_name) with register_lookup(CharField, Lower): self.assertCountEqual( Tag.objects.order_by().distinct('name__lower'), [self.t1, self.t2, self.t3, self.t4, self.t5], ) def test_distinct_not_implemented_checks(self): # distinct + annotate not allowed msg = 'annotate() + distinct(fields) is not implemented.' with self.assertRaisesMessage(NotImplementedError, msg): Celebrity.objects.annotate(Max('id')).distinct('id')[0] with self.assertRaisesMessage(NotImplementedError, msg): 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 msg = 'aggregate() + distinct(fields) not implemented.' with self.assertRaisesMessage(NotImplementedError, msg): 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.assertSequenceEqual(qs, [self.p1_o1, self.p2_o1, self.p3_o1]) qs = Staff.objects.distinct('name').order_by('name', '-id') qs = Staff.objects.filter(pk__in=qs).order_by('name') self.assertSequenceEqual(qs, [self.p1_o2, self.p2_o1, self.p3_o1]) 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')