[5.2.x] Fixed #36357 -- Skipped unique_together in inspectdb output for composite primary keys.

Thanks to Baptiste Mispelon for the report and quick fix, and to Simon
Charette and Jacob Walls for the reviews.

Co-authored-by: Natalia <124304+nessita@users.noreply.github.com>

Backport of 66f9eb0ff1e7147406318c5ba609729678e4e6f6 from main.

django/core/management/commands/inspectdb.py

@@ -391,7 +391,7 @@ class Command(BaseCommand):
                 columns = [
                     x for x in columns if x is not None and x in column_to_field_name
                 ]
-                if len(columns) > 1:
+                if len(columns) > 1 and not params["primary_key"]:
                     unique_together.append(
                         str(tuple(column_to_field_name[c] for c in columns))
                     )

docs/releases/5.2.1.txt

@@ -59,3 +59,7 @@ Bugfixes
 * Fixed a bug in composite primary key introspection that caused
   ``IntegerField`` to be wrongly identified as ``AutoField`` on SQLite
   (:ticket:`36358`).
+
+* Fixed a bug in Django 5.2 that caused a redundant ``unique_together``
+  constraint to be generated for composite primary keys when using
+  :djadmin:`inspectdb` (:ticket:`36357`).

tests/inspectdb/tests.py

@@ -637,3 +637,8 @@ class InspectDBTransactionalTests(TransactionTestCase):
         )
         self.assertIn(f"column_1 = models.{field_type}()", output)
         self.assertIn(f"column_2 = models.{field_type}()", output)
+
+    def test_composite_primary_key_not_unique_together(self):
+        out = StringIO()
+        call_command("inspectdb", "inspectdb_compositeprimarykeymodel", stdout=out)
+        self.assertNotIn("unique_together", out.getvalue())