在Django模型中，如何防止基于特定字段的删除? [英] Within a Django Model, how can I prevent a delete based on a particular field?

问题描述

在下面，我有一个Post模型. Post对象具有一个status字段，该字段可以是'unpublished'或'published'.

In the following, I have a Post model. A Post object has a status field that can be 'unpublished' or 'published'.

if status is 'published'，我想防止对象被删除，并希望将此逻辑封装在模型本身中.

if status is 'published', I'd like to prevent the object from being deleted, and would like to keep this logic encapsulated in the model itself.

from model_utils import Choices  # from Django-Model-Utils
from model_utils.fields import StatusField


class Post(model.Models)

    STATUS = Choices(
        ('unpublished', _('Unpublished')),
        ('published', _('Published')),
    )

    ...

    status = StatusField(default=STATUS.unpublished)

我该怎么做?如果使用QuerySet批量删除对象，则无法覆盖delete方法.我读过不要使用接收器，但是我不确定为什么.

How can I do this? Overriding the delete method won't work if the objects are being deleted in bulk with a QuerySet. I've read not to use receivers, but I'm not sure why.

推荐答案

这是我关注@Todor的评论:

This is what I have following @Todor's comment:

在signals.py中:

from django.db.models import ProtectedError
from django.db.models.signals import pre_delete
from django.dispatch import receiver

from .models import Post

@receiver(pre_delete, sender=Post, dispatch_uid='post_pre_delete_signal')
def protect_posts(sender, instance, using, **kwargs):
    if instance.status is 'unpublished': 
        pass
    else:  # Any other status types I add later will also be protected
        raise ProtectedError('Only unpublished posts can be deleted.')

我欢迎改进或获得更好的答案！

I welcome improvements or better answers!

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