Fix Postgres issue not dropping null constraint

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 List of the most important changes for each release.
 
+## 0.6.10
+- Fixes Django migration issue introduced in 0.6.7 allowing nullable fields with PostgreSQL backends
+
 ## 0.6.9
 - Fixes un-ordered selection of buffers during sync which can allow duplicates to be synced with PostgreSQL backends
 - Moves updating of database counters to occur in the same DB transaction as updates to the Store

morango/__init__.py

@@ -3,4 +3,4 @@
 from __future__ import unicode_literals
 
 default_app_config = "morango.apps.MorangoConfig"
-__version__ = "0.6.9"
+__version__ = "0.6.10"

morango/migrations/0020_postgres_fix_nullable.py

@@ -0,0 +1,33 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.29 on 2022-01-13 18:07
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+def apply(apps, schema_editor):
+    # sqlite does not allow ALTER COLUMN, but also isn't affected by this issue
+    if "postgresql" in schema_editor.connection.vendor:
+        schema_editor.execute("ALTER TABLE morango_transfersession ALTER COLUMN transfer_stage DROP NOT NULL")
+        schema_editor.execute("ALTER TABLE morango_transfersession ALTER COLUMN transfer_stage_status DROP NOT NULL")
+
+
+def revert(apps, schema_editor):
+    # sqlite does not allow ALTER COLUMN, but also isn't affected by this issue
+    if "postgresql" in schema_editor.connection.vendor:
+        schema_editor.execute("ALTER TABLE morango_transfersession ALTER COLUMN transfer_stage SET NOT NULL")
+        schema_editor.execute("ALTER TABLE morango_transfersession ALTER COLUMN transfer_stage_status SET NOT NULL")
+
+
+class Migration(migrations.Migration):
+    """
+    Applies nullable change made to 0018_auto_20210714_2216.py after it was released
+    """
+
+    dependencies = [
+        ("morango", "0019_auto_20220113_1807"),
+    ]
+
+    operations = [
+        migrations.RunPython(apply, reverse_code=revert),
+    ]

tests/testapp/tests/helpers.py

@@ -6,6 +6,9 @@
 
 import factory
 import mock
+from django.db import connection
+from django.db.migrations.executor import MigrationExecutor
+from django.test import TestCase
 from django.test.testcases import LiveServerTestCase
 from django.core.serializers.json import DjangoJSONEncoder
 from django.utils import timezone
@@ -442,3 +445,38 @@ def stage_status(self):
     def update_state(self, stage=None, stage_status=None):
         self._stage = stage or self._stage
         self._stage_status = stage_status or self._stage_status
+
+
+class TestMigrations(TestCase):
+    # Modified from https://www.caktusgroup.com/blog/2016/02/02/writing-unit-tests-django-migrations/
+
+    migrate_from = None
+    migrate_to = None
+    app = None
+
+    def setUp(self):
+        assert (
+            self.migrate_from and self.migrate_to
+        ), "TestCase '{}' must define migrate_from and migrate_to properties".format(
+            type(self).__name__
+        )
+
+        migrate_from = [(self.app, self.migrate_from)]
+        migrate_to = [(self.app, self.migrate_to)]
+        executor = MigrationExecutor(connection)
+        old_apps = executor.loader.project_state(migrate_from).apps
+
+        # Reverse to the original migration
+        executor.migrate(migrate_from)
+
+        self.setUpBeforeMigration(old_apps)
+
+        # Run the migration to test
+        executor = MigrationExecutor(connection)
+        executor.loader.build_graph()  # reload.
+        executor.migrate(migrate_to)
+
+        self.apps = executor.loader.project_state(migrate_to).apps
+
+    def setUpBeforeMigration(self, apps):
+        pass

tests/testapp/tests/test_migrations.py

@@ -0,0 +1,54 @@
+import uuid
+
+import pytest
+
+from django.conf import settings
+from django.db import connection
+from django.db.utils import IntegrityError
+from django.utils import timezone
+
+from .helpers import TestMigrations
+
+
+@pytest.mark.skipif(not settings.MORANGO_TEST_POSTGRESQL, reason="Only postgres")
+class MorangoNullableMigrationTest(TestMigrations):
+    """
+    Test migration that applies nullable status to `transfer_stage` and `transfer_stage_status`
+    """
+
+    app = "morango"
+    migrate_from = "0018_auto_20210714_2216"
+    migrate_to = "0020_postgres_fix_nullable"
+
+    def setUpBeforeMigration(self, apps):
+        # simulate as if 0018_auto_20210714_2216 hadn't applied Nullablity to the columns,
+        # a change which we added after the migration might have run on other
+        SyncSession = apps.get_model("morango", "SyncSession")
+
+        with connection.cursor() as cursor:
+            cursor.execute("ALTER TABLE morango_transfersession ALTER COLUMN transfer_stage SET NOT NULL")
+            cursor.execute("ALTER TABLE morango_transfersession ALTER COLUMN transfer_stage_status SET NOT NULL")
+
+        self.sync_session = SyncSession.objects.create(
+            id=uuid.uuid4().hex,
+            profile="facilitydata",
+            last_activity_timestamp=timezone.now(),
+        )
+
+    def test_nullable(self):
+        TransferSession = self.apps.get_model("morango", "TransferSession")
+
+        try:
+            transfer_session = TransferSession.objects.create(
+                id=uuid.uuid4().hex,
+                sync_session_id=self.sync_session.id,
+                push=True,
+                last_activity_timestamp=timezone.now(),
+                transfer_stage=None,
+                transfer_stage_status=None,
+            )
+        except IntegrityError:
+            self.fail("Couldn't create TransferSession with nullable fields")
+
+        self.assertIsNone(transfer_session.transfer_stage)
+        self.assertIsNone(transfer_session.transfer_stage_status)