Django扩展对象管理器引发'NoneType'对象没有属性'_meta' [英] Django extending objects manager raises 'NoneType' object has no attribute '_meta'

问题描述

我正在尝试按照 https://docs.djangoproject.com/en/dev/topics/db/managers/#modifying-initial-manager-querysets

我正在做这样的事情:

# the model, say Alpha
class MyManager(Manager):
    pass
Alpha.objects = MyManager()

我认为不应采取任何措施.但是只设置它会提高'NoneType' object has no attribute '_meta'.这怎么可能?我想我正在密切关注这个例子.

Which I think should not do anything. But just setting this raises 'NoneType' object has no attribute '_meta'. How is this possible? I think I am following the example rather closely.

在覆盖之前，我检查并Alpha.objects与之后的svGroup.objects.__class__.__bases__[0]()类型相同(因此它确实是子类的实例).

I checked and Alpha.objects before the overwrite is the same type as svGroup.objects.__class__.__bases__[0]() afterwards (so it is indeed an instance of a subclass).

我觉得这将是我更愚蠢的问题之一，但我无法弄清楚...

I have a feeling this is going to be one of my more stupid questions but I can't figure it out...

推荐答案

它应该在模型定义中.因为它是通过模型的元类的__new__方法处理的.

It should be inside the model definition. Because it's handling with the __new__ method of model's metaclass.

class Alpha(models.Model):
    ...
    objects = MyManager()

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