Fixed #34333 -- Fixed migration operations ordering when adding index/constraint on new foreign key.

Thanks Simon Charette and David Wobrock for reviews.

django/db/migrations/autodetector.py

@@ -1304,6 +1304,7 @@ class MigrationAutodetector:
 
     def generate_added_indexes(self):
         for (app_label, model_name), alt_indexes in self.altered_indexes.items():
+            dependencies = self._get_dependencies_for_model(app_label, model_name)
             for index in alt_indexes["added_indexes"]:
                 self.add_operation(
                     app_label,
@@ -1311,6 +1312,7 @@ class MigrationAutodetector:
                         model_name=model_name,
                         index=index,
                     ),
+                    dependencies=dependencies,
                 )
 
     def generate_removed_indexes(self):
@@ -1367,6 +1369,7 @@ class MigrationAutodetector:
             app_label,
             model_name,
         ), alt_constraints in self.altered_constraints.items():
+            dependencies = self._get_dependencies_for_model(app_label, model_name)
             for constraint in alt_constraints["added_constraints"]:
                 self.add_operation(
                     app_label,
@@ -1374,6 +1377,7 @@ class MigrationAutodetector:
                         model_name=model_name,
                         constraint=constraint,
                     ),
+                    dependencies=dependencies,
                 )
 
     def generate_removed_constraints(self):
@@ -1425,6 +1429,22 @@ class MigrationAutodetector:
             dependencies.append((through_app_label, through_object_name, None, True))
         return dependencies
 
+    def _get_dependencies_for_model(self, app_label, model_name):
+        """Return foreign key dependencies of the given model."""
+        dependencies = []
+        model_state = self.to_state.models[app_label, model_name]
+        for field in model_state.fields.values():
+            if field.is_relation:
+                dependencies.extend(
+                    self._get_dependencies_for_foreign_key(
+                        app_label,
+                        model_name,
+                        field,
+                        self.to_state,
+                    )
+                )
+        return dependencies
+
     def _get_altered_foo_together_operations(self, option_name):
         for app_label, model_name in sorted(self.kept_model_keys):
             old_model_name = self.renamed_models.get(

tests/migrations/test_autodetector.py

@@ -2720,6 +2720,65 @@ class AutodetectorTests(BaseAutodetectorTests):
             changes, "testapp", 0, 0, model_name="author", constraint=added_constraint
         )
 
+    def test_add_constraints_with_new_model(self):
+        book_with_unique_title_and_pony = ModelState(
+            "otherapp",
+            "Book",
+            [
+                ("id", models.AutoField(primary_key=True)),
+                ("title", models.CharField(max_length=200)),
+                ("pony", models.ForeignKey("otherapp.Pony", models.CASCADE)),
+            ],
+            {
+                "constraints": [
+                    models.UniqueConstraint(
+                        fields=["title", "pony"],
+                        name="unique_title_pony",
+                    )
+                ]
+            },
+        )
+        changes = self.get_changes(
+            [self.book_with_no_author],
+            [book_with_unique_title_and_pony, self.other_pony],
+        )
+
+        self.assertNumberMigrations(changes, "otherapp", 1)
+        self.assertOperationTypes(
+            changes,
+            "otherapp",
+            0,
+            ["CreateModel", "AddField", "AddConstraint"],
+        )
+
+    def test_add_index_with_new_model(self):
+        book_with_index_title_and_pony = ModelState(
+            "otherapp",
+            "Book",
+            [
+                ("id", models.AutoField(primary_key=True)),
+                ("title", models.CharField(max_length=200)),
+                ("pony", models.ForeignKey("otherapp.Pony", models.CASCADE)),
+            ],
+            {
+                "indexes": [
+                    models.Index(fields=["title", "pony"], name="index_title_pony"),
+                ]
+            },
+        )
+        changes = self.get_changes(
+            [self.book_with_no_author],
+            [book_with_index_title_and_pony, self.other_pony],
+        )
+
+        self.assertNumberMigrations(changes, "otherapp", 1)
+        self.assertOperationTypes(
+            changes,
+            "otherapp",
+            0,
+            ["CreateModel", "AddField", "AddIndex"],
+        )
+
     def test_remove_constraints(self):
         """Test change detection of removed constraints."""
         changes = self.get_changes(