Fixed #25833 -- Added support for non-atomic migrations.

Added the Migration.atomic attribute which can be set to False
for non-atomic migrations.

tests/migrations/test_commands.py

@@ -362,6 +362,19 @@ class MigrateTests(MigrationTestBase):
         # Cleanup by unmigrating everything
         call_command("migrate", "migrations", "zero", verbosity=0)
 
+    @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations_non_atomic"})
+    def test_sqlmigrate_for_non_atomic_migration(self):
+        """
+        Transaction wrappers aren't shown for non-atomic migrations.
+        """
+        out = six.StringIO()
+        call_command("sqlmigrate", "migrations", "0001", stdout=out)
+        output = out.getvalue().lower()
+        queries = [q.strip() for q in output.splitlines()]
+        if connection.ops.start_transaction_sql():
+            self.assertNotIn(connection.ops.start_transaction_sql().lower(), queries)
+        self.assertNotIn(connection.ops.end_transaction_sql().lower(), queries)
+
     @override_settings(
         INSTALLED_APPS=[
             "migrations.migrations_test_apps.migrated_app",

tests/migrations/test_executor.py

@@ -100,6 +100,33 @@ class ExecutorTests(MigrationTestBase):
         self.assertTableNotExists("migrations_author")
         self.assertTableNotExists("migrations_book")
 
+    @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations_non_atomic"})
+    def test_non_atomic_migration(self):
+        """
+        Applying a non-atomic migration works as expected.
+        """
+        executor = MigrationExecutor(connection)
+        with self.assertRaisesMessage(RuntimeError, "Abort migration"):
+            executor.migrate([("migrations", "0001_initial")])
+        self.assertTableExists("migrations_publisher")
+        migrations_apps = executor.loader.project_state(("migrations", "0001_initial")).apps
+        Publisher = migrations_apps.get_model("migrations", "Publisher")
+        self.assertTrue(Publisher.objects.exists())
+        self.assertTableNotExists("migrations_book")
+
+    @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations_atomic_operation"})
+    def test_atomic_operation_in_non_atomic_migration(self):
+        """
+        An atomic operation is properly rolled back inside a non-atomic
+        migration.
+        """
+        executor = MigrationExecutor(connection)
+        with self.assertRaisesMessage(RuntimeError, "Abort migration"):
+            executor.migrate([("migrations", "0001_initial")])
+        migrations_apps = executor.loader.project_state(("migrations", "0001_initial")).apps
+        Editor = migrations_apps.get_model("migrations", "Editor")
+        self.assertFalse(Editor.objects.exists())
+
     @override_settings(MIGRATION_MODULES={
         "migrations": "migrations.test_migrations",
         "migrations2": "migrations2.test_migrations_2",

tests/migrations/test_migrations_atomic_operation/0001_initial.py

@@ -0,0 +1,25 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+def raise_error(apps, schema_editor):
+    # Test atomic operation in non-atomic migration is wrapped in transaction
+    Editor = apps.get_model('migrations', 'Editor')
+    Editor.objects.create(name='Test Editor')
+    raise RuntimeError('Abort migration')
+
+
+class Migration(migrations.Migration):
+    atomic = False
+
+    operations = [
+        migrations.CreateModel(
+            "Editor",
+            [
+                ("name", models.CharField(primary_key=True, max_length=255)),
+            ],
+        ),
+        migrations.RunPython(raise_error, atomic=True),
+    ]

tests/migrations/test_migrations_non_atomic/0001_initial.py

@@ -0,0 +1,32 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+def raise_error(apps, schema_editor):
+    # Test operation in non-atomic migration is not wrapped in transaction
+    Publisher = apps.get_model('migrations', 'Publisher')
+    Publisher.objects.create(name='Test Publisher')
+    raise RuntimeError('Abort migration')
+
+
+class Migration(migrations.Migration):
+    atomic = False
+
+    operations = [
+        migrations.CreateModel(
+            "Publisher",
+            [
+                ("name", models.CharField(primary_key=True, max_length=255)),
+            ],
+        ),
+        migrations.RunPython(raise_error),
+        migrations.CreateModel(
+            "Book",
+            [
+                ("title", models.CharField(primary_key=True, max_length=255)),
+                ("publisher", models.ForeignKey("migrations.Publisher", models.SET_NULL, null=True)),
+            ],
+        ),
+    ]