Fixed #31667 -- Made __in lookup ignore None values.

django/db/models/lookups.py

@@ -366,10 +366,12 @@ class In(FieldGetDbPrepValueIterableMixin, BuiltinLookup):
             )
 
         if self.rhs_is_direct_value():
+            # Remove None from the list as NULL is never equal to anything.
             try:
                 rhs = OrderedSet(self.rhs)
+                rhs.discard(None)
             except TypeError:  # Unhashable items in self.rhs
-                rhs = self.rhs
+                rhs = [r for r in self.rhs if r is not None]
 
             if not rhs:
                 raise EmptyResultSet

tests/lookup/tests.py

@@ -576,8 +576,6 @@ class LookupTests(TestCase):
         self.assertQuerysetEqual(Article.objects.none().iterator(), [])
 
     def test_in(self):
-        # using __in with an empty list should return an empty query set
-        self.assertQuerysetEqual(Article.objects.filter(id__in=[]), [])
         self.assertQuerysetEqual(
             Article.objects.exclude(id__in=[]),
             [
@@ -591,6 +589,9 @@ class LookupTests(TestCase):
             ]
         )
 
+    def test_in_empty_list(self):
+        self.assertSequenceEqual(Article.objects.filter(id__in=[]), [])
+
     def test_in_different_database(self):
         with self.assertRaisesMessage(
             ValueError,
@@ -603,6 +604,31 @@ class LookupTests(TestCase):
         query = Article.objects.filter(slug__in=['a%d' % i for i in range(1, 8)]).values('pk').query
         self.assertIn(' IN (a1, a2, a3, a4, a5, a6, a7) ', str(query))
 
+    def test_in_ignore_none(self):
+        with self.assertNumQueries(1) as ctx:
+            self.assertSequenceEqual(
+                Article.objects.filter(id__in=[None, self.a1.id]),
+                [self.a1],
+            )
+        sql = ctx.captured_queries[0]['sql']
+        self.assertIn('IN (%s)' % self.a1.pk, sql)
+
+    def test_in_ignore_solo_none(self):
+        with self.assertNumQueries(0):
+            self.assertSequenceEqual(Article.objects.filter(id__in=[None]), [])
+
+    def test_in_ignore_none_with_unhashable_items(self):
+        class UnhashableInt(int):
+            __hash__ = None
+
+        with self.assertNumQueries(1) as ctx:
+            self.assertSequenceEqual(
+                Article.objects.filter(id__in=[None, UnhashableInt(self.a1.id)]),
+                [self.a1],
+            )
+        sql = ctx.captured_queries[0]['sql']
+        self.assertIn('IN (%s)' % self.a1.pk, sql)
+
     def test_error_messages(self):
         # Programming errors are pointed out with nice error messages
         with self.assertRaisesMessage(