[5.0.x] Fixed #35002 -- Made UniqueConstraints with fields respect nulls_distinct.

Regression in 595a2abb58e04caa4d55fb2589bb80fb2a8fdfa1.

Backport of 54cb1a7e160089cea438f50fdb70aaaf6823786e from main

2 files changed, 25 insertions, 2 deletions

diff --git a/django/db/backends/base/schema.py b/django/db/backends/base/schema.py
index a311dc432e..1062e9feca 100644
--- a/django/db/backends/base/schema.py
+++ b/django/db/backends/base/schema.py
@@ -111,7 +111,7 @@ class BaseDatabaseSchemaEditor:
 
     sql_create_unique = (
         "ALTER TABLE %(table)s ADD CONSTRAINT %(name)s "
-        "UNIQUE (%(columns)s)%(deferrable)s"
+        "UNIQUE%(nulls_distinct)s (%(columns)s)%(deferrable)s"
     )
     sql_delete_unique = sql_delete_constraint
 
diff --git a/tests/schema/tests.py b/tests/schema/tests.py
index a37b49b31d..046097366c 100644
--- a/tests/schema/tests.py
+++ b/tests/schema/tests.py
@@ -3474,7 +3474,7 @@ class SchemaTests(TransactionTestCase):
                 editor.add_constraint(Author, constraint)
 
     @skipUnlessDBFeature("supports_nulls_distinct_unique_constraints")
-    def test_unique_constraint_nulls_distinct(self):
+    def test_unique_constraint_index_nulls_distinct(self):
         with connection.schema_editor() as editor:
             editor.create_model(Author)
         nulls_distinct = UniqueConstraint(
@@ -3497,6 +3497,29 @@ class SchemaTests(TransactionTestCase):
         self.assertNotIn(nulls_distinct.name, constraints)
         self.assertNotIn(nulls_not_distinct.name, constraints)
 
+    @skipUnlessDBFeature("supports_nulls_distinct_unique_constraints")
+    def test_unique_constraint_nulls_distinct(self):
+        with connection.schema_editor() as editor:
+            editor.create_model(Author)
+        constraint = UniqueConstraint(
+            fields=["height", "weight"], name="constraint", nulls_distinct=False
+        )
+        with connection.schema_editor() as editor:
+            editor.add_constraint(Author, constraint)
+        Author.objects.create(name="", height=None, weight=None)
+        Author.objects.create(name="", height=1, weight=None)
+        Author.objects.create(name="", height=None, weight=1)
+        with self.assertRaises(IntegrityError):
+            Author.objects.create(name="", height=None, weight=None)
+        with self.assertRaises(IntegrityError):
+            Author.objects.create(name="", height=1, weight=None)
+        with self.assertRaises(IntegrityError):
+            Author.objects.create(name="", height=None, weight=1)
+        with connection.schema_editor() as editor:
+            editor.remove_constraint(Author, constraint)
+        constraints = self.get_constraints(Author._meta.db_table)
+        self.assertNotIn(constraint.name, constraints)
+
     @skipIfDBFeature("supports_nulls_distinct_unique_constraints")
     def test_unique_constraint_nulls_distinct_unsupported(self):
         # UniqueConstraint is ignored on databases that don't support