django-logicaldelete 1.1 Beta 1 Dev3

A base model that provides some extras for your models
Developer comments

django-logicaldelete is a small and simple app that I threw together to get some reuse out of something I do in nearly every project and every model I create. It's too easy for good data to get deleted and it be unrecoverable. It's also too easy to fix this by overriding the model's delete() method and just flagging records as deleted and then leveraging Django's Managers to override default behavior so that logically deleted items are not returned in querysets.

There are two exceptions however, that I have found useful to this rule.

 1. In the admin I like to see everything with an indicator of whether or not it has been deleted, with the ability to filter down to just active records, (or deleted for that matter).
 2. I still think it is a valid request when an item is fetched for by it's primary key value, that the object should return, even if it is marked as deleted.

Using django-logicaldelete

Using the app is pretty simple:

 1. Put the logicaldelete sub-folder in your Python Path.
 2. Inherit from logicaldelete.models.Model for all models that you wish to share in this functionality.
 3. Create and/or Register admins for each of these models using logicaldelete.admin.ModelAdmin

Additional

Logical deletes are handled by date stamping a date_removed column. In addition, a date_created and date_modified columns will be populated as a convenience.

Possible Extensions

You can easily subclass these two classes to provide generic and useful functionality to your models.

UUID Primary Key

I typically using UUID fields for my primary keys because they enable me to shard my tables if and when I need to, in addition, they provide an obfuscated id to my data (people can't determine how many of a certain object I have in my database, if I don't want them to know, but simply looking an an integer id in the URL).

Sequence Field

Many times I find it useful to have an integer field on my models that allow for and explicitly controlled sequencing. I normally implement this as a sort descending implementation where the data is sorted from high to low by sequence value.

In order to to implement this you'd subclass both the Model and ModelAdmin, where the Model would be an obvious simple addition of an IntegerField, the ModelAdmin, would override get_query_set, to do something like:

class SequencedModel(logicaldelete.models.Model):
 sequence = models.IntegerField()


class MyLogicalDeletedManager(logicaldelete.models.LogicalDeletedManager):
 def get_query_set(self):
 if self.model:
 qs = super(MyLogicalDeletedManager, self).get_query_set().filter(date_removed__isnull=True)
 if SequencedModel in inspect.getmro(self.model):
 qs = qs.order_by('-sequence')
 return qs

last updated on:
February 23rd, 2011, 7:06 GMT
price:
FREE!
developed by:
Patrick Altman
homepage:
github.com
license type:
MIT/X Consortium License 
category:
ROOT \ Internet \ HTTP (WWW)

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What's New in version 1.1 Beta 1
  • Changed everything to all_with_deleted on LogicalDeleteManager
  • LogicalDeleteManager moved from logicaldelete.models to logicaldelete.managers
  • Removed deleted and everything querysets from logicaldelete.models.Model
read full changelog

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