django-softdelete-it 0.1

示例

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

如果要为模型实现一个新的Manager，只需与其他管理器一起继承SoftDeleteManager。

如果要为模型实现新的QuerySet，则需要执行以下操作：

1. 继承SoftDeleteQuerySet
2. 写管理器继承SoftDeleteManager，它在其__init__()方法（如示例所示）中定义软删除功能，并重写get_queryset()方法（如示例所示）
3. 编写继承SoftDeleteModel的模型类并使用上述新定义的Manager方法（如示例中所示）

queryset

允许为项目创建QuerySet，以便在创建新项目时如果未提供作者，则将在对象中添加一个默认作者。

#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)

如何实现软删除功能：

1. 创建一个新的软删除应用程序，整个软删除功能的代码在其models.py文件中实现。
2. 添加了一个抽象的SoftDeleteModel，其中包含一个deleted属性，即UUIDField。对于未删除的对象，它将保留None，对于已删除的对象，它将保留一个新的uuid4。
3. SoftDeleteQuerySet实现以将默认django的delete方法重写为soft-delete对象，而不是硬删除它们。
4. undelete()，hard_delete()，only_deleted()方法在同一个QuerySet类中实现，以提供额外的功能。
5. SoftDeleteManger通过重写get_queryset()方法实现以使用上面的queryset。
6. queryset的delete方法必须重写才能支持bulk_delete功能。
7. 在上述删除方法定义前后调用pre_delete和post_delete信号。
8. 使用django管理实用程序中的nestedobjects软删除所有相关对象。
9. 两个管理器，objects和all_objects返回undeleted，所有对象都实现了。