如何从现场添加经理

发布于 2024-07-14 22:01:51 字数 541 浏览 9 评论 0原文

我想要做的是，当某些模型使用我的字段时，它会自动将自定义管理器添加到该模型。

据我所知，contibute_to_class提供了这样的功能

class MyCustomField(CharField):
    def contribute_to_class(self, cls, name):
        super(MyCustomField, self).contribute_to_class(cls, name)
        setattr(cls, 'custom_manager', CustomManager())

问题是，在我的自定义管理器中，我使用 self.model._default_manager 对默认管理器进行查询，但是当我尝试这样做时，django 说 AttributeError: 'NoneType' object has no attribute '_default_manager'

如果我不使用contribute_to_class 并在我的模型类旁边编写自定义管理器，它会按预期工作。可能是什么问题？

原文

What i want to do is when some model use my field, it will automaticaly add custom manager to that model.

As far as i know, contibute_to_class provide such functionality

class MyCustomField(CharField):
    def contribute_to_class(self, cls, name):
        super(MyCustomField, self).contribute_to_class(cls, name)
        setattr(cls, 'custom_manager', CustomManager())

The problem is that in my custom manager i use self.model._default_manager to do queries on default manager but when i try to do it, django says AttributeError: 'NoneType' object has no attribute '_default_manager'

If i dont use contribute_to_class and write custom manager iside my model class, it works as expected. What can be the problem?

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甜点 2024-07-21 22:01:51

管理器，就像字段一样，有一个contribute_to_class方法，如果你不调用它，它们将无法正确设置。正确的调用方法是使用 Model.add_to_class：

class MyCustomField(CharField):
    def contribute_to_class(self, cls, name):
        super(MyCustomField, self).contribute_to_class(cls, name)
        cls.add_to_class('custom_manager', CustomManager())

Managers, just like Fields, have a contribute_to_class method, and if you don't call it they won't be set up properly. The correct way to call it is by using Model.add_to_class:

class MyCustomField(CharField):
    def contribute_to_class(self, cls, name):
        super(MyCustomField, self).contribute_to_class(cls, name)
        cls.add_to_class('custom_manager', CustomManager())

回复收藏 0 原文

因为看清所以看轻 2024-07-21 22:01:51

class MyCustomField(CharField):
    def contribute_to_class(self, cls, name):
        super(MyCustomField, self).contribute_to_class(cls, name)
        manager = CustomManager()
        manager.model = cls
        setattr(cls, 'custom_manager', manager)

class MyCustomField(CharField):
    def contribute_to_class(self, cls, name):
        super(MyCustomField, self).contribute_to_class(cls, name)
        manager = CustomManager()
        manager.model = cls
        setattr(cls, 'custom_manager', manager)

回复收藏 0 原文

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