Django 自定义软删除Model

软删除介绍

简单的说，就是当执行删除操作的时候，不真正执行删除操作，而是在逻辑上删除一条记录。这样做的好处是可以统计数据，可以进行恢复操作等等。
Managers 是django models 提供的一个用于提供数据库查询操作的接口，对于Django应用程序中的每个model都会至少存在一个Manager
详细：https://docs.djangoproject.com/zh-hans/3.2/topics/db/managers/

django实现软删除model

from django.db import models
from django.db.models.query import QuerySet

# 自定义软删除查询基类

class SoftDeletableQuerySetMixin(object):
    """
    QuerySet for SoftDeletableModel. Instead of removing instance sets
    its ``is_deleted`` field to True.
    """
    def delete(self):
        """
        Soft delete objects from queryset (set their ``is_deleted``
        field to True)
        """
        self.update(is_deleted=True)


class SoftDeletableQuerySet(SoftDeletableQuerySetMixin, QuerySet):
    pass


class SoftDeletableManagerMixin(object):
    """
    Manager that limits the queryset by default to show only not deleted
    instances of model.
    """
    _queryset_class = SoftDeletableQuerySet

    def get_queryset(self):
        """
        Return queryset limited to not deleted entries.
        """
        kwargs = {'model': self.model, 'using': self._db}
        if hasattr(self, '_hints'):
            kwargs['hints'] = self._hints

        return self._queryset_class(**kwargs).filter(is_deleted=False)


class SoftDeletableManager(SoftDeletableManagerMixin, models.Manager):
    pass

# 自定义软删除抽象基类
class SoftDeletableModel(models.Model):
    """
    An abstract base class model with a ``is_deleted`` field that
    marks entries that are not going to be used anymore, but are
    kept in db for any reason.
    Default manager returns only not-deleted entries.
    """
    is_deleted = models.BooleanField(default=False)

    class Meta:
        abstract = True  # 成功发送Signal信号需要将abstract设置为true
        auto_created = False

    objects = SoftDeletableManager()

    def delete(self, using=None, soft=True, *args, **kwargs):
        """
        Soft delete object (set its ``is_deleted`` field to True).
        Actually delete object if setting ``soft`` to False.
        """
        if soft:
            self.is_deleted = True
            self.save(using=using)
        else:
            return super(SoftDeletableModel, self).delete(using=using, *args, **kwargs)

model demo代码开发

class Server(SoftDeletableModel):
    id = models.AutoField(primary_key=True)
    local_ip = models.CharField('内网ip', max_length=30, blank=True, null=True)
  
    class Meta:
        db_table = 'dbmanage_server'

class ServerBase(models.Model):
    id = models.AutoField(primary_key=True)
    local_ip = models.CharField('内网ip', max_length=30, blank=True, null=True)
    is_deleted = models.BooleanField('是否删除', default=False)

    class Meta:
        managed = False  # 在migrate时不会创建该表
        db_table = 'dbmanage_server'

继承了软删除模型类SoftDeletableModel的模型server，在进行migrate建表操作时，自动会给Server表添加上一个is_deleted字段。后续的数据删除操作中只需要执行delete()，即可将数据的is_deleted设置为True。查询操作时，不需要加上条件限制，自动会返回is_deleted=False的数据。

Tips

1：Server模型无法发送信号
增加代码abstract = True（具体细节不太了解，看源码里要求的）
2：需要查询已经删除掉的数据
有时候想要展示已经删除的数据，但是Server模型里是自动过滤掉删除数据的。
增加一个ServerBase模型类，在进行查询时使用该类，记得增加managed=Fasle，这样在migrate时不会django不会去创建该表。