使用django-model-utils自动下载到子类 [英] Automatically downcast to subclass using django-model-utils

问题描述

我有多个用户模型..所有继承使用自定义管理器的基本模型

I have multiple user models .. all inheriting a Base model with a custom manager

class BaseUser(models.Model):
    [...]

    objects = UserManager()


class StaffUser(BaseUser):
    [...]

class Customer(BaseUser):
    [...]

managers.py

managers.py

from model_utils.managers import InheritanceManager

class UserManager(..., InheritanceManager):
    [...]

通过从django-model-utils继承InheritanceManager，我可以对继承的模型进行自动下载。所以例如，如果我有3个对象，每个用户类型之一：

By inheriting the InheritanceManager from django-model-utils, I can do automatic downcasting for inherited models. So for example, if I have 3 objects, one of each user type:

user = BaseUser.objects.select_subclasses()

[Customer: [e-mail], BaseUser: [e-mail], StaffUser: [e-mail]]

为此，我必须明确地调用 .select_subclasses（），

To do that, I had to explicitly call .select_subclasses(),

但是我想自动进行下载，而无需调用 .select_subclasses（）

But I want to do the downcasting automatically without having to call .select_subclasses()

所以我试过：

class UserManager（...，InheritanceManager）：

class UserManager(..., InheritanceManager):

    def get_queryset(self, *args, **kwargs):
        queryset = super(UserManager, self).get_queryset()
        return queryset.get_subclass(*args, **kwargs)

但是现在当我尝试使用：

But now when I try to use:

user = EmailUser.objects.all()

我得到这个： p>

I get this:

MultipleObjectsReturned: get() returned more than one BaseUser -- it returned 3!

是否可以使用django-model-utils对继承的模型进行自动下载？

Is it possible to do automatic downcasting for inherited models using django-model-utils?

推荐答案

我想出来了！

from model_utils.managers import InheritanceQuerySet

class UserManager([...]):

    def get_queryset(self):
        return InheritanceQuerySet(self.model).select_subclasses()

我没有继承 InheritanceManager ，而是使用 InheritanceQuerySet 。

I didn't have to inherit InheritanceManager, instead use the InheritanceQuerySet.

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