from django.db import connection from django.db.models import CharField, F, 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 non-unique query is not allowed. base_qs = Celebrity.objects.all() msg = "Cannot combine a unique query with a non-unique query." with self.assertRaisesMessage(TypeError, msg): base_qs.distinct("id") & base_qs # Combining queries with different distinct_fields is not allowed. msg = "Cannot combine queries with different distinct fields." with self.assertRaisesMessage(TypeError, msg): 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_sliced_queryset(self): msg = "Cannot create distinct fields once a slice has been taken." with self.assertRaisesMessage(TypeError, msg): Staff.objects.all()[0:5].distinct("name") 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") def test_distinct_on_mixed_case_annotation(self): qs = ( Staff.objects.annotate( nAmEAlIaS=F("name"), ) .distinct("nAmEAlIaS") .order_by("nAmEAlIaS") ) self.assertSequenceEqual(qs, [self.p1_o1, self.p2_o1, self.p3_o1])