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Description:

djangosoftdeleteit 0.1

Add soft-delete functionality to desired models.

Quick start
Follow steps mentioned below to add soft-delete feature in any model of your django app.

pip install django-softdelete-it
Add soft_delete_it to your INSTALLED_APPS setting like this:
INSTALLED_APPS = [
...
'soft_delete_it',
]

Import SoftDeleteModel from soft_delete_it app to your model file like this:
from soft_delete_it import SoftDeleteModel

Inherit SoftDeleteModel class to your model class. It will add following features:

objects manager’s behavior will change such that:

delete() method which will soft delete instances
will always return return only ‘non soft deleted’ objects
hard_delete()` method to hard delete the objects

all_objects manager:

will always return both soft deleted and non soft deleted objects
hard_delete() method to hard delete the objects
only_deleted() method to return only soft deleted objects
undelete() method to un-delete soft-deleted objects

Example
from django.db import models
from soft_delete_it.models import SoftDeleteModel

class Author(SoftDeleteModel):
name = models.CharField(max_length=50)
dob = models.DateField()

class Article(SoftDeleteModel):
title = models.CharField(max_length=50)
body = models.TextField(null=True)
author = models.ForeignKey(Author, on_delete=models.CASCADE, related_name='articles')

Bob = Author.objects.create(name='bob', dob='2000-12-12')
John = Author.objects.create(name='john', dob='1990-10-12')

Author.objects.all() # return QuerySet with 2 objects
Bob.delete() # Bob is soft-deleted
Author.objects.all() # return QuerySet with 1 object, John
Author.all_objects.all() # return QuerySet with 2 object, Bob and John
Bob.undelete() # un-deletes Bob object
Author.objects.all() # return QuerySet with 2 objects

article1 = Article(title='Bob The Builder', body='')
article1.author = Bob
article1.save()

Article.objects.all() # return QuerySet with 1 object, article1

Bob.delete() # soft-deletes both Bob and article1 as Article's author field is on_delete_cascade and it Inherits SoftDeleteModel
If you are implementing a new Manager for a model, simply inherit SoftDeleteManager as well along with other Managers.

If you are implementing a new QuerySet for a model, you will need to do following:

Inherit SoftDeleteQuerySet
Write Manager inheriting SoftDeleteManager which defines soft-delete functionality in it’s __init__() method(as in the example) and override get_queryset() method(as in the example)
Write model class inheriting SoftDeleteModel and uses above new defined Manager method(as in the example)

Example with QuerySet
Lets create a QuerySet for Article such that if no author is provided while creating a new article, one default author will be added in object.
#Creating a default author object first
default_author = Author.objects.create(name='default')

#Implementing QuerySet
from soft_delete_it.models import SoftDeleteModel, SoftDeleteQuerySet, SoftDeleteManager

class ArticleQuerySet(SoftDeleteQuerySet):

def create(self, **kwargs):
try:
author = kwargs['author']
except KeyError:
kwargs['author'] = Author.objects.get(name='default')
article = super(ArticleQuerySet, self).create(**kwargs)
return article

class ArticleManager(SoftDeleteManager):

def __init__(self, *args, **kwargs):
self.deleted_also = kwargs.get('deleted_also', False)
super(ArticleManager, self).__init__(*args, **kwargs)

def get_queryset(self):
'''return all unsoft-deleted objects'''
if self.deleted_also:
return ArticleQuerySet(self.model)
return ArticleQuerySet(self.model).filter(deleted=None)

class Article(SoftDeleteModel):
title = models.CharField(max_length=50)
body = models.TextField(null=True)
author = models.ForeignKey(Author, on_delete=models.CASCADE, related_name='articles')

objects = ArticleManager.from_queryset(ArticleQuerySet)()
all_objects = ArticleManager.from_queryset(ArticleQuerySet)(deleted_also=True)

How soft-deletion functionality is implemented:

Create a new soft_delete app, whole code for soft-deletion functionality is implemented in its models.py file.
An abstract SoftDeleteModel added which contains a deleted attribute which is a UUIDField. It will hold None for undeleted object and a new uuid4 for deleted objects.
SoftDeleteQuerySet implemented to override default django’s delete method to soft-delete objects instead of hard deleting them.
undelete(), hard_delete(), only_deleted() methods are implemented in same QuerySet class to provide extra features.
SoftDeleteManger implemented to use above QuerySet by overriding get_queryset() method.
QuerySet’s delete method is necessary to override to support bulk_delete feature.
Call pre_delete and post_delete signals before and after the definition of above delete method.
Use NestedObjects from django admin utils to soft-delete all related objects.
Two managers, objects and all_objects to return undeleted, all objects are implemented.