make DAB RBAC migrations reversible

Put in the nulling cases

Author: AlanCoding

ansible_base/rbac/migrations/0005_remote_permissions_data.py

@@ -1,6 +1,6 @@
 # Generated by Django 4.2.23 on 2025-06-30 12:48
 
-from django.db import migrations
+from django.db import migrations, models
 
 
 def create_types_if_needed(apps, schema_editor):
@@ -54,4 +54,15 @@ class Migration(migrations.Migration):
     operations = [
         migrations.RunPython(create_types_if_needed, migrations.RunPython.noop),
         migrations.RunPython(migrate_content_type, migrations.RunPython.noop),
+        # Make the content_type fields nullable so the reverse migrations are possible
+        migrations.AlterField(
+            model_name='dabpermission',
+            name='content_type',
+            field=models.ForeignKey(help_text='The content type this permission will apply to.', null=True, on_delete=models.deletion.CASCADE, to='contenttypes.contenttype', verbose_name='content type'),
+        ),
+        migrations.AlterField(
+            model_name='objectrole',
+            name='content_type',
+            field=models.ForeignKey(help_text='The content type of the subject of permission assignments. Duplicated from related RoleDefinition.', null=True, on_delete=models.deletion.CASCADE, to='contenttypes.contenttype'),
+        ),
     ]

ansible_base/rbac/migrations/0006_remote_data_reverse.py

@@ -0,0 +1,45 @@
+# Generated by Django 4.2.23 on 2025-06-30 12:48
+
+from django.db import migrations
+
+
+def migrate_content_type_forward_noop(apps, schema_editor):
+    """Forward no-op: data migration already happened in 0005."""
+    pass
+
+
+def migrate_content_type_reverse(apps, schema_editor):
+    """Reverse migration: undo what 0005 did by copying data back from new_content_type to content_type.
+    
+    When this reverse runs, we're going from state after 0005 back to state after 0004.
+    After 0005: data was copied from content_type to new_content_type
+    To reverse: copy from new_content_type back to content_type, and clear new_content_type
+    """
+    django_ct_cls = apps.get_model('contenttypes', 'ContentType')
+    
+    for model_name in ('dabpermission', 'objectrole', 'roledefinition', 'roleuserassignment', 'roleteamassignment'):
+        cls = apps.get_model('dab_rbac', model_name)
+        for obj in cls.objects.all():
+            new_ct = obj.new_content_type
+            if new_ct:
+                try:
+                    # Find the corresponding Django ContentType by app_label and model
+                    django_ct = django_ct_cls.objects.get(app_label=new_ct.app_label, model=new_ct.model)
+                    obj.content_type = django_ct
+                    obj.save()
+                except Exception as e:
+                    raise RuntimeError(
+                        f"Failed to get Django content type for a {model_name} pk={obj.pk}, "
+                        f"DABContentType app_label='{new_ct.app_label}', model='{new_ct.model}'"
+                    ) from e
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('dab_rbac', '0005_remote_permissions_data'),
+    ]
+
+    operations = [
+        migrations.RunPython(migrate_content_type_forward_noop, migrate_content_type_reverse),
+    ] 

ansible_base/rbac/migrations/0006_remote_permissions_removals.py renamed to ansible_base/rbac/migrations/0007_remote_permissions_removals.py

@@ -6,7 +6,7 @@
 class Migration(migrations.Migration):
 
     dependencies = [
-        ('dab_rbac', '0005_remote_permissions_data'),
+        ('dab_rbac', '0006_remote_data_reverse'),
     ]
 
     operations = [

ansible_base/rbac/migrations/0007_remote_permissions_cleanup.py renamed to ansible_base/rbac/migrations/0008_remote_permissions_cleanup.py

@@ -6,7 +6,7 @@
 class Migration(migrations.Migration):
 
     dependencies = [
-        ('dab_rbac', '0006_remote_permissions_removals'),
+        ('dab_rbac', '0007_remote_permissions_removals'),
     ]
 
     operations = [