🗃️ [#4267] Make migration more robust

src/openforms/registrations/contrib/objects_api/migrations/0019_add_default_objects_api_group.py

@@ -1,9 +1,8 @@
 # Generated by Django 4.2.11 on 2024-07-02 15:18
 
 from django.db import migrations
-
-from django.db.migrations.state import StateApps
 from django.db.backends.base.schema import BaseDatabaseSchemaEditor
+from django.db.migrations.state import StateApps
 
 
 def add_default_objects_api_group(
@@ -13,17 +12,33 @@ def add_default_objects_api_group(
     ObjectsAPIGroupConfig = apps.get_model(
         "registrations_objects_api", "ObjectsAPIGroupConfig"
     )
+    backends_qs = FormRegistrationBackend.objects.filter(backend="objects_api")
+    # nothing to do if there are no relevant backends
+    if not backends_qs.exists():
+        return
 
     objects_api_group_config = ObjectsAPIGroupConfig.objects.order_by("pk").first()
     if objects_api_group_config is None:
-        # Because this migration runs after registrations_objects_api/0017_move_singleton_data,
-        # Having no Objects API Group means we had no solo config in the first place, thus
-        # it is safe to assume no Objects API registration backend was set up.
-        return
+        # This shouldn't happen because of:
+        # * upgrade checks
+        # * operations in registrations_objects_api/0017_move_singleton_data
+        #
+        # BUT that doesn't mean it's impossible, like on continuously deployed
+        # environments... For those cases, we generate a (knowingly broken)
+        # configuration so that migrations don't crash and options have at least the
+        # right shape so that we can trust the type annotations.
+        objects_api_group_config = ObjectsAPIGroupConfig.objects.create(
+            name="AUTO_GENERATED - FIXME",
+            # DeprecationWarning
+            # Open Forms 3.0 will drop the nullable fields, so this data migration needs
+            # to be gone by then.
+            objects_service=None,
+            objecttypes_service=None,
+            drc_service=None,
+            catalogi_service=None,
+        )
 
-    for registration_backend in FormRegistrationBackend.objects.filter(
-        backend="objects_api"
-    ):
+    for registration_backend in backends_qs:
         registration_backend.options.setdefault(
             "objects_api_group", objects_api_group_config.pk
         )

src/openforms/registrations/contrib/objects_api/tests/test_migrations.py

@@ -313,6 +313,40 @@ def test_sets_default_objects_api_group(self) -> None:
         )
 
 
+class AddDefaultObjectsAPIGroupWithBrokenStateMigrationTests(TestMigrations):
+    app = "registrations_objects_api"
+    migrate_from = "0018_remove_objectsapiconfig_catalogi_service_and_more"
+    migrate_to = "0019_add_default_objects_api_group"
+
+    def setUpBeforeMigration(self, apps: StateApps) -> None:
+        Form = apps.get_model("forms", "Form")
+        FormRegistrationBackend = apps.get_model("forms", "FormRegistrationBackend")
+        ObjectsAPIGroupConfig = apps.get_model(
+            "registrations_objects_api", "ObjectsAPIGroupConfig"
+        )
+
+        form = Form.objects.create(name="test form")
+        FormRegistrationBackend.objects.create(
+            form=form,
+            name="Objects API backend",
+            key="backend",
+            backend="objects_api",
+        )
+        assert not ObjectsAPIGroupConfig.objects.exists()
+
+    def test_sets_default_objects_api_group(self) -> None:
+        FormRegistrationBackend = self.apps.get_model(
+            "forms", "FormRegistrationBackend"
+        )
+        ObjectsAPIGroupConfig = self.apps.get_model(
+            "registrations_objects_api", "ObjectsAPIGroupConfig"
+        )
+        auto_created_config = ObjectsAPIGroupConfig.objects.get()
+
+        backend = FormRegistrationBackend.objects.get()
+        self.assertEqual(backend.options["objects_api_group"], auto_created_config.pk)
+
+
 class ObjecttypeUrltoUuidMigrationTests(TestMigrations):
     app = "registrations_objects_api"
     migrate_from = "0019_add_default_objects_api_group"