cancan101 / django-permanent

Yet another approach to creation of non-deletable and non-removable from db restorable django models.

Django Permanent

Yet another approach to provide soft (logical) delete or masking (thrashing) django models instead of deleting them physically from db.

Models

To create non-deletable model just inherit it form the PermanentModel.:

class MyModel(PermanentModel):
    pass

It automatically changes delete behaviour, to hide model instead of deleting. restore() method.:

>>> a = MyModel.objects.create(pk=1)
>>> b = MyModel.objects.create(pk=2)
>>> MyModel.objects.count()
2
>>> a.delete()
>>> MyModel.objects.count()
1

To recover model just call its restore method.:

>>> a.restore()
>>> MyModel.objects.count()
2

User Force kwarg to enforce physical deletion.:

>>> a.delete(force=True) # Will act as the default django delete
>>> MyModel._base_manager.count()
0

If you need to restore deleted model instead of creating the same use restore_on_create attribute.:

class MyModel(PermanentModel):
    class Permanent:
      restore_on_create = True

In this case QuerySet provides check existence of same attributes object and restores it if it was removed, creates a new if not.

Managers

It changes default model manager to ignore deleted objects. And adds deleted_objects manager to find the last ones.:

>>> MyModel.objects.count()
2
>>> a.delete()
>>> MyModel.objects.count()
1
>>> MyModel.deleted_objects.count()
1
>>> MyModel.all_objects.count()
2
>>> MyModel._base_manager.count()
2

QuerySet

Query set delete method will act as the default django delete, with the one exception - all related PermanentModel children will be marked as deleted, the usual models will be deleted physically:

>>> MyModel.objects.all().delete()

You can still force django query set physical deletion:

>>> MyModel.objects.all().delete(force=True)

Using custom querysets (requires django-model-utils)

1. Inherit your query set from PermanentQuerySet:

   class ServerFileQuerySet(PermanentQuerySet)
       pass
   

2. Wrap it in the permanent_queryset or deleted_queryset in you model manager declaration:

   class MyModel(PermanentModel)
       objects = MultiPassThroughManager(ServerFileQuerySet, NonDeletedQuerySet)
       deleted_objects = MultiPassThroughManager(ServerFileQuerySet, DeletedQuerySet)
       all_objects = MultiPassThroughManager(ServerFileQuerySet, PermanentQuerySet)
   

Method get_restore_or_create

1. Check existence of the object.
2. Restore it was deleted.
3. Create new one, if it wasn't ever created.

Field name

By default field is named removed, but you can override it by PERMANENT_FIELD variable in your settings.py.:

PERMANENT_FIELD = 'deleted'

Requirements

Django min 1.6.x required. To cover Django 1.5 needs use 0.1.4 branch.