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A simple Django app to add soft-delete functionality to desired models

Project Description
# django-softdelete-it


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.

1. Add "soft_delete_it" to your INSTALLED_APPS setting like this:
```
INSTALLED_APPS = [
...
'soft_delete_it',
]
```
2. Import `SoftDeleteModel` from soft_delete app to your model file like this:
from soft_delete_it import SoftDeleteModel
3. 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='5-5-80')
John = Author.objects.create(name='john', dob='5-5-80')

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:
1. Inherit `SoftDeleteQuerySet`
2. 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)
3. Write model class inheriting `SoftDeleteModel` and uses above new defined `Manager` method(as in the example)

### Example

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:

1. Create a new soft_delete app, whole code for soft-deletion functionality is implemented in its models.py file.
2. An abstract `SoftDeleteModel` added which contains a `deleted` attribuate which is a BooleanField. It will hold `False` for undeleted object and `True` for deleted objects.
3. `SoftDeleteQuerySet` implemented to override default django's `delete` method to `soft-delete` objects instead of hard deleting them.
4. `undelete()`, `hard_delete()`, `only_deleted()` methods are implemented in same QuerySet class to provide extra features.
5. `SoftDeleteManger` implemented to use above QuerySet by overriding `get_queryset()` method.
6. QuerySet's delete method is necessary to override to support `bulk_delete` feature.
7. Call pre_delete and post_delete signals before and after the definition of above delete method.
8. Use NestedObjects from django admin utils[3] to soft-delete all related objects.
9. Two managers, objects and all_objects to return undeleted, all objects are implemented.
Release History

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This version
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0.1

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