django之自定義軟刪除Model的方法

更新時間：2019年08月14日 16:10:28 作者：我愛學python

這篇文章主要介紹了django之自定義軟刪除Model的方法，文中通過示例代碼介紹的非常詳細，對大家的學習或者工作具有一定的參考學習價值，需要的朋友們下面隨著小編來一起學習學習吧

軟刪除

簡單的說，就是當執(zhí)行刪除操作的時候，不正真執(zhí)行刪除操作，而是在邏輯上刪除一條記錄。這樣做的好處是可以統(tǒng)計數據，可以進行恢復操作等等。

預備知識

Managers

Managers 是django models 提供的一個用于提供數據庫查詢操作的接口，對于Django應用程序中的每個model都會至少存在一個Manager

詳細：https://docs.djangoproject.com/en/dev/topics/db/managers/

django實現軟刪除model

firstly，

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

# 自定義軟刪除查詢基類
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

secondly，

# 自定義軟刪除抽象基類
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

  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)

class CustomerInfo(SoftDeletableModel):
  nid = models.AutoField(primary_key=True)
  category = models.ForeignKey("CustomerCategory", to_field="nid", on_delete=models.CASCADE, verbose_name='客戶分類',
                 db_constraint=False)
  company = models.CharField(max_length=64, verbose_name="公司名稱")

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