Refactor distribution migration 0032

This allows the migration to be reverted.

[noissue]

pulp_rpm/app/migrations/0032_new_distribution_model.py

@@ -4,73 +4,74 @@
 import django.db.models.deletion
 
 
-pks_to_delete = []
-
-
-def migrate_data_from_old_master_model_to_new_master_model(apps, schema_editor):
+def migrate_data_from_old_model_to_new_model_up(apps, schema_editor):
+    """ Move objects from RpmDistribution to NewRpmDistribution."""
     RpmDistribution = apps.get_model('rpm', 'RpmDistribution')
-    CoreDistribution = apps.get_model('core', 'Distribution')
-    for old_file_distribution in RpmDistribution.objects.all():
+    NewRpmDistribution = apps.get_model('rpm', 'NewRpmDistribution')
+    for distribution in RpmDistribution.objects.all():
         with transaction.atomic():
-            new_master_model_entry = CoreDistribution(
-                pulp_id=old_file_distribution.pulp_id,
-                pulp_created=old_file_distribution.pulp_created,
-                pulp_last_updated=old_file_distribution.pulp_last_updated,
-                pulp_type=old_file_distribution.pulp_type,
-                name=old_file_distribution.name,
-                base_path=old_file_distribution.base_path,
-                content_guard=old_file_distribution.content_guard,
-                remote=old_file_distribution.remote,
-                publication=old_file_distribution.publication,
-            )
-            new_master_model_entry.save()
-            old_file_distribution.distribution_ptr = new_master_model_entry
-            old_file_distribution.save()
-            pks_to_delete.append(old_file_distribution.pulp_id)
+            NewRpmDistribution(
+                pulp_id=distribution.pulp_id,
+                pulp_created=distribution.pulp_created,
+                pulp_last_updated=distribution.pulp_last_updated,
+                pulp_type=distribution.pulp_type,
+                name=distribution.name,
+                base_path=distribution.base_path,
+                content_guard=distribution.content_guard,
+                remote=distribution.remote,
+                publication=distribution.publication
+            ).save()
+            distribution.delete()
 
 
-def delete_remaining_old_master_model_entries(apps, schema_editor):
-    with connection.cursor() as cursor:
-        for pk in pks_to_delete:
-            cursor.execute("DELETE from core_basedistribution WHERE pulp_id = %s", [pk])
+def migrate_data_from_old_model_to_new_model_down(apps, schema_editor):
+    """ Move objects from NewRpmDistribution to RpmDistribution."""
+    RpmDistribution = apps.get_model('rpm', 'RpmDistribution')
+    NewRpmDistribution = apps.get_model('rpm', 'NewRpmDistribution')
+    for distribution in NewRpmDistribution.objects.all():
+        with transaction.atomic():
+            RpmDistribution(
+                pulp_id=distribution.pulp_id,
+                pulp_created=distribution.pulp_created,
+                pulp_last_updated=distribution.pulp_last_updated,
+                pulp_type=distribution.pulp_type,
+                name=distribution.name,
+                base_path=distribution.base_path,
+                content_guard=distribution.content_guard,
+                remote=distribution.remote,
+                publication=distribution.publication
+            ).save()
+            distribution.delete()
 
 
 class Migration(migrations.Migration):
+    atomic = False
 
     dependencies = [
         ('core', '0062_add_new_distribution_mastermodel'),
         ('rpm', '0031_ulnremote'),
     ]
 
     operations = [
-        migrations.AddField(
-            model_name='rpmdistribution',
-            name='distribution_ptr',
-            field=models.OneToOneField(auto_created=True, null=True, default=None,
-                                       on_delete=django.db.models.deletion.CASCADE,
-                                       parent_link=True, primary_key=False,
-                                       related_name='rpm_rpmdistribution', serialize=False,
-                                       to='core.Distribution'),
-            preserve_default=False,
+        migrations.CreateModel(
+            name='NewRpmDistribution',
+            fields=[
+                ('distribution_ptr', models.OneToOneField(auto_created=True, on_delete=django.db.models.deletion.CASCADE, parent_link=True, primary_key=True, related_name='rpm_rpmdistribution', serialize=False, to='core.Distribution')),
+            ],
+            options={
+                'default_related_name': '%(app_label)s_%(model_name)s',
+            },
+            bases=('core.distribution',),
         ),
-        migrations.RunPython(migrate_data_from_old_master_model_to_new_master_model),
-        migrations.RemoveField(
-            model_name='rpmdistribution',
-            name='basedistribution_ptr',
+        migrations.RunPython(
+            code=migrate_data_from_old_model_to_new_model_up,
+            reverse_code=migrate_data_from_old_model_to_new_model_down,
         ),
-        migrations.AlterField(
-            model_name='rpmdistribution',
-            name='distribution_ptr',
-            field=models.OneToOneField(auto_created=True,
-                                       on_delete=django.db.models.deletion.CASCADE,
-                                       parent_link=True, primary_key=True,
-                                       related_name='rpm_rpmdistribution', serialize=False,
-                                       to='core.Distribution'),
-            preserve_default=False,
+        migrations.DeleteModel(
+            name='RpmDistribution',
         ),
-        migrations.RemoveField(
-            model_name='rpmdistribution',
-            name='publication',
+        migrations.RenameModel(
+            old_name='NewRpmDistribution',
+            new_name='RpmDistribution',
         ),
-        migrations.RunPython(delete_remaining_old_master_model_entries),
     ]