Fixed #28658 -- Added DISTINCT handling to the Aggregate class.

4 files changed, 35 insertions, 5 deletions

diff --git a/tests/aggregation/tests.py b/tests/aggregation/tests.py
index a55ccfbfa2..75d2ecb1c5 100644
--- a/tests/aggregation/tests.py
+++ b/tests/aggregation/tests.py
@@ -1026,7 +1026,7 @@ class AggregateTestCase(TestCase):
         # test completely changing how the output is rendered
         def lower_case_function_override(self, compiler, connection):
             sql, params = compiler.compile(self.source_expressions[0])
-            substitutions = {'function': self.function.lower(), 'expressions': sql}
+            substitutions = {'function': self.function.lower(), 'expressions': sql, 'distinct': ''}
             substitutions.update(self.extra)
             return self.template % substitutions, params
         setattr(MySum, 'as_' + connection.vendor, lower_case_function_override)
@@ -1053,7 +1053,7 @@ class AggregateTestCase(TestCase):
 
         # test overriding all parts of the template
         def be_evil(self, compiler, connection):
-            substitutions = {'function': 'MAX', 'expressions': '2'}
+            substitutions = {'function': 'MAX', 'expressions': '2', 'distinct': ''}
             substitutions.update(self.extra)
             return self.template % substitutions, ()
         setattr(MySum, 'as_' + connection.vendor, be_evil)
diff --git a/tests/aggregation_regress/tests.py b/tests/aggregation_regress/tests.py
index 29b32c4987..2b3948a0b4 100644
--- a/tests/aggregation_regress/tests.py
+++ b/tests/aggregation_regress/tests.py
@@ -11,6 +11,7 @@ from django.db.models import (
     Avg, Case, Count, DecimalField, F, IntegerField, Max, Q, StdDev, Sum,
     Value, Variance, When,
 )
+from django.db.models.aggregates import Aggregate
 from django.test import (
     TestCase, ignore_warnings, skipUnlessAnyDBFeature, skipUnlessDBFeature,
 )
@@ -1496,6 +1497,16 @@ class AggregationTests(TestCase):
         qs = Author.objects.values_list('age', flat=True).annotate(age_count=Count('age')).filter(age_count__gt=1)
         self.assertSequenceEqual(qs, [29])
 
+    def test_allow_distinct(self):
+        class MyAggregate(Aggregate):
+            pass
+        with self.assertRaisesMessage(TypeError, 'MyAggregate does not allow distinct'):
+            MyAggregate('foo', distinct=True)
+
+        class DistinctAggregate(Aggregate):
+            allow_distinct = True
+        DistinctAggregate('foo', distinct=True)
+
 
 class JoinPromotionTests(TestCase):
     def test_ticket_21150(self):
diff --git a/tests/backends/sqlite/tests.py b/tests/backends/sqlite/tests.py
index bddaf8620f..c681d39775 100644
--- a/tests/backends/sqlite/tests.py
+++ b/tests/backends/sqlite/tests.py
@@ -4,6 +4,7 @@ import unittest
 
 from django.db import connection, transaction
 from django.db.models import Avg, StdDev, Sum, Variance
+from django.db.models.aggregates import Aggregate
 from django.db.models.fields import CharField
 from django.db.utils import NotSupportedError
 from django.test import (
@@ -34,6 +35,17 @@ class Tests(TestCase):
                     **{'complex': aggregate('last_modified') + aggregate('last_modified')}
                 )
 
+    def test_distinct_aggregation(self):
+        class DistinctAggregate(Aggregate):
+            allow_distinct = True
+        aggregate = DistinctAggregate('first', 'second', distinct=True)
+        msg = (
+            "SQLite doesn't support DISTINCT on aggregate functions accepting "
+            "multiple arguments."
+        )
+        with self.assertRaisesMessage(NotSupportedError, msg):
+            connection.ops.check_expression_support(aggregate)
+
     def test_memory_db_test_name(self):
         """A named in-memory db should be allowed where supported."""
         from django.db.backends.sqlite3.base import DatabaseWrapper
diff --git a/tests/expressions/tests.py b/tests/expressions/tests.py
index 2ed928915a..ee3676e64a 100644
--- a/tests/expressions/tests.py
+++ b/tests/expressions/tests.py
@@ -1481,18 +1481,22 @@ class ReprTests(SimpleTestCase):
 
     def test_aggregates(self):
         self.assertEqual(repr(Avg('a')), "Avg(F(a))")
-        self.assertEqual(repr(Count('a')), "Count(F(a), distinct=False)")
-        self.assertEqual(repr(Count('*')), "Count('*', distinct=False)")
+        self.assertEqual(repr(Count('a')), "Count(F(a))")
+        self.assertEqual(repr(Count('*')), "Count('*')")
         self.assertEqual(repr(Max('a')), "Max(F(a))")
         self.assertEqual(repr(Min('a')), "Min(F(a))")
         self.assertEqual(repr(StdDev('a')), "StdDev(F(a), sample=False)")
         self.assertEqual(repr(Sum('a')), "Sum(F(a))")
         self.assertEqual(repr(Variance('a', sample=True)), "Variance(F(a), sample=True)")
 
+    def test_distinct_aggregates(self):
+        self.assertEqual(repr(Count('a', distinct=True)), "Count(F(a), distinct=True)")
+        self.assertEqual(repr(Count('*', distinct=True)), "Count('*', distinct=True)")
+
     def test_filtered_aggregates(self):
         filter = Q(a=1)
         self.assertEqual(repr(Avg('a', filter=filter)), "Avg(F(a), filter=(AND: ('a', 1)))")
-        self.assertEqual(repr(Count('a', filter=filter)), "Count(F(a), distinct=False, filter=(AND: ('a', 1)))")
+        self.assertEqual(repr(Count('a', filter=filter)), "Count(F(a), filter=(AND: ('a', 1)))")
         self.assertEqual(repr(Max('a', filter=filter)), "Max(F(a), filter=(AND: ('a', 1)))")
         self.assertEqual(repr(Min('a', filter=filter)), "Min(F(a), filter=(AND: ('a', 1)))")
         self.assertEqual(repr(StdDev('a', filter=filter)), "StdDev(F(a), filter=(AND: ('a', 1)), sample=False)")
@@ -1501,6 +1505,9 @@ class ReprTests(SimpleTestCase):
             repr(Variance('a', sample=True, filter=filter)),
             "Variance(F(a), filter=(AND: ('a', 1)), sample=True)"
         )
+        self.assertEqual(
+            repr(Count('a', filter=filter, distinct=True)), "Count(F(a), distinct=True, filter=(AND: ('a', 1)))"
+        )
 
 
 class CombinableTests(SimpleTestCase):