Fixed #23315: Operational dependency fail with mixed create/add

2 files changed, 73 insertions, 76 deletions

diff --git a/django/db/migrations/autodetector.py b/django/db/migrations/autodetector.py
index 19cbe2a2f6..e67c8aa902 100644
--- a/django/db/migrations/autodetector.py
+++ b/django/db/migrations/autodetector.py
@@ -286,7 +286,7 @@ class MigrationAutodetector(object):
                 if not chop_mode:
                     chop_mode = True
                 else:
-                    raise ValueError("Cannot resolve operation dependencies")
+                    raise ValueError("Cannot resolve operation dependencies: %r" % self.generated_operations)
             num_ops = new_num_ops
 
         # OK, add in internal dependencies among the migrations
@@ -361,10 +361,13 @@ class MigrationAutodetector(object):
         else:
             raise ValueError("Can't handle dependency %r" % (dependency, ))
 
-    def add_operation(self, app_label, operation, dependencies=None):
+    def add_operation(self, app_label, operation, dependencies=None, beginning=False):
         # Dependencies are (app_label, model_name, field_name, create/delete as True/False)
         operation._auto_deps = dependencies or []
-        self.generated_operations.setdefault(app_label, []).append(operation)
+        if beginning:
+            self.generated_operations.setdefault(app_label, []).insert(0, operation)
+        else:
+            self.generated_operations.setdefault(app_label, []).append(operation)
 
     def swappable_first_key(self, item):
         """
@@ -429,7 +432,7 @@ class MigrationAutodetector(object):
         that might be deferred (e.g. unique_together, index_together)
         """
         added_models = set(self.new_model_keys) - set(self.old_model_keys)
-        for app_label, model_name in sorted(added_models, key=self.swappable_first_key):
+        for app_label, model_name in sorted(added_models, key=self.swappable_first_key, reverse=True):
             model_state = self.to_state.models[app_label, model_name]
             # Gather related fields
             related_fields = {}
@@ -481,6 +484,7 @@ class MigrationAutodetector(object):
                     bases=model_state.bases,
                 ),
                 dependencies=dependencies,
+                beginning=True,
             )
             # Generate operations for each related field
             for name, field in sorted(related_fields.items()):
diff --git a/tests/migrations/test_autodetector.py b/tests/migrations/test_autodetector.py
index 86f8ce3982..cb02b7aacd 100644
--- a/tests/migrations/test_autodetector.py
+++ b/tests/migrations/test_autodetector.py
@@ -131,12 +131,13 @@ class AutodetectorTests(TestCase):
         operation = migration.operations[operation_index]
         for attr, value in attrs.items():
             if getattr(operation, attr, None) != value:
-                self.fail("Attribute mismatch for %s.%s op #%s, %s (expected %r):\n%s" % (
+                self.fail("Attribute mismatch for %s.%s op #%s, %s (expected %r, got %r):\n%s" % (
                     app_label,
                     migration.name,
-                    operation_index + 1,
+                    operation_index,
                     attr,
                     value,
+                    getattr(operation, attr, None),
                     self.repr_changes(changes),
                 ))
 
@@ -403,21 +404,14 @@ class AutodetectorTests(TestCase):
         after = self.make_project_state([self.author_with_publisher, self.publisher])
         autodetector = MigrationAutodetector(before, after)
         changes = autodetector._detect_changes()
-        # Right number of migrations?
-        self.assertEqual(len(changes['testapp']), 1)
-        # Right number of actions?
-        migration = changes['testapp'][0]
-        self.assertEqual(len(migration.operations), 3)
-        # Right actions?
-        action = migration.operations[0]
-        self.assertEqual(action.__class__.__name__, "CreateModel")
-        action = migration.operations[1]
-        self.assertEqual(action.__class__.__name__, "CreateModel")
-        # Third action might vanish one day if the optimizer improves.
-        action = migration.operations[2]
-        self.assertEqual(action.__class__.__name__, "AddField")
+        # Right number/type of migrations?
+        self.assertNumberMigrations(changes, 'testapp', 1)
+        self.assertOperationTypes(changes, 'testapp', 0, ["CreateModel", "CreateModel", "AddField"])
+        self.assertOperationAttributes(changes, "testapp", 0, 0, name="Author")
+        self.assertOperationAttributes(changes, "testapp", 0, 1, name="Publisher")
+        self.assertOperationAttributes(changes, "testapp", 0, 2, name="publisher")
         # Right dependencies?
-        self.assertEqual(migration.dependencies, [])
+        self.assertEqual(changes['testapp'][0].dependencies, [])
 
     def test_circular_fk_dependency(self):
         """
@@ -430,30 +424,18 @@ class AutodetectorTests(TestCase):
         autodetector = MigrationAutodetector(before, after)
         changes = autodetector._detect_changes()
         # Right number of migrations?
-        self.assertEqual(len(changes['testapp']), 1)
-        self.assertEqual(len(changes['otherapp']), 2)
-        # Right number of actions?
-        migration1 = changes['testapp'][0]
-        self.assertEqual(len(migration1.operations), 2)
-        migration2 = changes['otherapp'][0]
-        self.assertEqual(len(migration2.operations), 1)
-        migration3 = changes['otherapp'][1]
-        self.assertEqual(len(migration3.operations), 1)
-        # Right actions?
-        action = migration1.operations[0]
-        self.assertEqual(action.__class__.__name__, "CreateModel")
-        self.assertEqual(action.name, "Author")
-        self.assertEqual(len(action.fields), 3)
-        action = migration2.operations[0]
-        self.assertEqual(action.__class__.__name__, "CreateModel")
-        self.assertEqual(len(action.fields), 2)
-        action = migration3.operations[0]
-        self.assertEqual(action.__class__.__name__, "AddField")
-        self.assertEqual(action.name, "author")
+        self.assertNumberMigrations(changes, 'testapp', 1)
+        self.assertNumberMigrations(changes, 'otherapp', 2)
+        # Right types?
+        self.assertOperationTypes(changes, 'testapp', 0, ["CreateModel", "CreateModel"])
+        self.assertOperationTypes(changes, 'otherapp', 0, ["CreateModel"])
+        self.assertOperationTypes(changes, 'otherapp', 1, ["AddField"])
+        self.assertOperationAttributes(changes, "testapp", 0, 0, name="Author")
+        self.assertOperationAttributes(changes, "testapp", 0, 1, name="Publisher")
         # Right dependencies?
-        self.assertEqual(migration1.dependencies, [("otherapp", "auto_1")])
-        self.assertEqual(migration2.dependencies, [])
-        self.assertEqual(set(migration3.dependencies), set([("testapp", "auto_1"), ("otherapp", "auto_1")]))
+        self.assertEqual(changes['testapp'][0].dependencies, [("otherapp", "auto_1")])
+        self.assertEqual(changes['otherapp'][0].dependencies, [])
+        self.assertEqual(set(changes['otherapp'][1].dependencies), set([("otherapp", "auto_1"), ("testapp", "auto_1")]))
 
     def test_same_app_circular_fk_dependency(self):
         """
@@ -465,24 +447,14 @@ class AutodetectorTests(TestCase):
         after = self.make_project_state([self.author_with_publisher, self.publisher_with_author])
         autodetector = MigrationAutodetector(before, after)
         changes = autodetector._detect_changes()
-        # Right number of migrations?
-        self.assertEqual(len(changes['testapp']), 1)
-        # Right number of actions?
-        migration1 = changes['testapp'][0]
-        self.assertEqual(len(migration1.operations), 4)
-        # Right actions?
-        action = migration1.operations[0]
-        self.assertEqual(action.__class__.__name__, "CreateModel")
-        action = migration1.operations[1]
-        self.assertEqual(action.__class__.__name__, "CreateModel")
-        action = migration1.operations[2]
-        self.assertEqual(action.__class__.__name__, "AddField")
-        self.assertEqual(action.name, "publisher")
-        action = migration1.operations[3]
-        self.assertEqual(action.__class__.__name__, "AddField")
-        self.assertEqual(action.name, "author")
+        # Right number/type of migrations?
+        self.assertNumberMigrations(changes, 'testapp', 1)
+        self.assertOperationTypes(changes, 'testapp', 0, ["CreateModel", "CreateModel", "AddField"])
+        self.assertOperationAttributes(changes, "testapp", 0, 0, name="Author")
+        self.assertOperationAttributes(changes, "testapp", 0, 1, name="Publisher")
+        self.assertOperationAttributes(changes, "testapp", 0, 2, name="publisher")
         # Right dependencies?
-        self.assertEqual(migration1.dependencies, [])
+        self.assertEqual(changes['testapp'][0].dependencies, [])
 
     def test_same_app_circular_fk_dependency_and_unique_together(self):
         """
@@ -495,23 +467,13 @@ class AutodetectorTests(TestCase):
         after = self.make_project_state([self.knight, self.rabbit])
         autodetector = MigrationAutodetector(before, after)
         changes = autodetector._detect_changes()
-        # Right number of migrations?
-        self.assertEqual(len(changes['eggs']), 1)
-        # Right number of actions?
-        migration1 = changes['eggs'][0]
-        self.assertEqual(len(migration1.operations), 3)
-        # Right actions?
-        action = migration1.operations[0]
-        self.assertEqual(action.__class__.__name__, "CreateModel")
-        action = migration1.operations[1]
-        self.assertEqual(action.__class__.__name__, "CreateModel")
-        self.assertEqual(action.name, "Rabbit")
-        self.assertFalse("unique_together" in action.options)
-        action = migration1.operations[2]
-        self.assertEqual(action.__class__.__name__, "AlterUniqueTogether")
-        self.assertEqual(action.name, "rabbit")
+        # Right number/type of migrations?
+        self.assertNumberMigrations(changes, 'eggs', 1)
+        self.assertOperationTypes(changes, 'eggs', 0, ["CreateModel", "CreateModel", "AlterUniqueTogether"])
+        self.assertFalse("unique_together" in changes['eggs'][0].operations[0].options)
+        self.assertFalse("unique_together" in changes['eggs'][0].operations[1].options)
         # Right dependencies?
-        self.assertEqual(migration1.dependencies, [])
+        self.assertEqual(changes['eggs'][0].dependencies, [])
 
     def test_unique_together(self):
         "Tests unique_together detection"
@@ -1110,3 +1072,34 @@ class AutodetectorTests(TestCase):
         self.assertOperationTypes(changes, 'testapp', 0, ["AddField"])
         self.assertOperationAttributes(changes, 'testapp', 0, 0, name="book")
         self.assertEqual(changes['testapp'][0].dependencies, [("otherapp", "__first__")])
+
+    def test_circular_dependency_mixed_addcreate(self):
+        """
+        Tests that the dependency resolver knows to put all CreateModel
+        before AddField and not become unsolvable (#23315)
+        """
+        address = ModelState("a", "Address", [
+            ("id", models.AutoField(primary_key=True)),
+            ("country", models.ForeignKey("b.DeliveryCountry")),
+        ])
+        person = ModelState("a", "Person", [
+            ("id", models.AutoField(primary_key=True)),
+        ])
+        apackage = ModelState("b", "APackage", [
+            ("id", models.AutoField(primary_key=True)),
+            ("person", models.ForeignKey("a.person")),
+        ])
+        country = ModelState("b", "DeliveryCountry", [
+            ("id", models.AutoField(primary_key=True)),
+        ])
+        # Make state
+        before = self.make_project_state([])
+        after = self.make_project_state([address, person, apackage, country])
+        autodetector = MigrationAutodetector(before, after)
+        changes = autodetector._detect_changes()
+        # Right number of migrations?
+        self.assertNumberMigrations(changes, 'a', 2)
+        self.assertNumberMigrations(changes, 'b', 1)
+        self.assertOperationTypes(changes, 'a', 0, ["CreateModel", "CreateModel"])
+        self.assertOperationTypes(changes, 'a', 1, ["AddField"])
+        self.assertOperationTypes(changes, 'b', 0, ["CreateModel", "CreateModel"])