Fixed #22960: Bad handling of relations as PKs in autodetector

django/db/migrations/autodetector.py

@@ -413,10 +413,14 @@ class MigrationAutodetector(object):
             model_state = self.to_state.models[app_label, model_name]
             # Gather related fields
             related_fields = {}
+            primary_key_rel = None
             for field in self.new_apps.get_model(app_label, model_name)._meta.local_fields:
                 if field.rel:
                     if field.rel.to:
-                        related_fields[field.name] = field
+                        if field.primary_key:
+                            primary_key_rel = field.rel.to
+                        else:
+                            related_fields[field.name] = field
                     # through will be none on M2Ms on swapped-out models;
                     # we can treat lack of through as auto_created=True, though.
                     if getattr(field.rel, "through", None) and not field.rel.through._meta.auto_created:
@@ -439,6 +443,14 @@ class MigrationAutodetector(object):
                 if isinstance(base, six.string_types) and "." in base:
                     base_app_label, base_name = base.split(".", 1)
                     dependencies.append((base_app_label, base_name, None, True))
+            # Depend on the other end of the primary key if it's a relation
+            if primary_key_rel:
+                dependencies.append((
+                        primary_key_rel._meta.app_label,
+                        primary_key_rel._meta.object_name,
+                        None,
+                        True
+                    ))
             # Generate creation operation
             self.add_operation(
                 app_label,

tests/migrations/test_autodetector.py

@@ -72,6 +72,7 @@ class AutodetectorTests(TestCase):
     custom_user_no_inherit = ModelState("thirdapp", "CustomUser", [("id", models.AutoField(primary_key=True)), ("username", models.CharField(max_length=255))])
     aardvark = ModelState("thirdapp", "Aardvark", [("id", models.AutoField(primary_key=True))])
     aardvark_based_on_author = ModelState("testapp", "Aardvark", [], bases=("testapp.Author", ))
+    aardvark_pk_fk_author = ModelState("testapp", "Aardvark", [("id", models.OneToOneField("testapp.Author", primary_key=True))])
     knight = ModelState("eggs", "Knight", [("id", models.AutoField(primary_key=True))])
     rabbit = ModelState("eggs", "Rabbit", [("id", models.AutoField(primary_key=True)), ("knight", models.ForeignKey("eggs.Knight")), ("parent", models.ForeignKey("eggs.Rabbit"))], {"unique_together": [("parent", "knight")]})
 
@@ -987,7 +988,6 @@ class AutodetectorTests(TestCase):
         self.assertOperationAttributes(changes, 'thirdapp', 0, 0, name="CustomUser")
         self.assertOperationAttributes(changes, 'thirdapp', 0, 1, name="Aardvark")
 
-    @override_settings(AUTH_USER_MODEL="thirdapp.CustomUser")
     def test_bases_first(self):
         """
         Tests that bases of other models come first.
@@ -1002,3 +1002,18 @@ class AutodetectorTests(TestCase):
         self.assertOperationTypes(changes, 'testapp', 0, ["CreateModel", "CreateModel"])
         self.assertOperationAttributes(changes, 'testapp', 0, 0, name="Author")
         self.assertOperationAttributes(changes, 'testapp', 0, 1, name="Aardvark")
+
+    def test_pk_fk_included(self):
+        """
+        Tests that a relation used as the primary key is kept as part of CreateModel.
+        """
+        # Make state
+        before = self.make_project_state([])
+        after = self.make_project_state([self.aardvark_pk_fk_author, self.author_name])
+        autodetector = MigrationAutodetector(before, after)
+        changes = autodetector._detect_changes()
+        # Right number of migrations?
+        self.assertNumberMigrations(changes, 'testapp', 1)
+        self.assertOperationTypes(changes, 'testapp', 0, ["CreateModel", "CreateModel"])
+        self.assertOperationAttributes(changes, 'testapp', 0, 0, name="Author")
+        self.assertOperationAttributes(changes, 'testapp', 0, 1, name="Aardvark")