将 `issubclass()` 与 Django 模型结合使用

发布于 2024-12-12 07:46:57 字数 587 浏览 3 评论 0原文

我有一些 Django 模型，比如说

class Foo(models.Model):
    class Meta:
        abstract = True

class Bar(Foo)
    pass

我希望能够找到从 Foo 继承的所有模型，以便用它们执行任务。这应该很容易，就像

from django.db import models
from myapp.models import Foo

for model in models.get_models():
    if issubclass(model, Foo):
        do_something()

唉，这不起作用，因为 issubclass(Bar, Foo) 报告 False，可能是 Django 元类内部工作的结果初始化模型。

有没有办法检查 Django 模型是否是抽象 Django 模型的后代？

请不要建议鸭子打字作为解决方案。在这种情况下，我真的很想知道是否存在子类关系。

原文

I have some Django models, say

class Foo(models.Model):
    class Meta:
        abstract = True

class Bar(Foo)
    pass

I would like to be able to find all models inheriting from Foo, in order to perform a task with them. It should be easy, like

from django.db import models
from myapp.models import Foo

for model in models.get_models():
    if issubclass(model, Foo):
        do_something()

Alas, this does not work, since issubclass(Bar, Foo) reports False, probably as a result of the inner working of the Django metaclass that initializes the models.

Is there a way to check whether a Django models is a descendant of an abstract Django model?

Please, do not suggest duck typing as the solution. In this case, I really would like to know whether a subclass relation exists.

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黒涩兲箜 2024-12-19 07:46:57

问题是如何导入类。而不是：

from myapp.models import Foo

使用：

from myproject.myapp.models import Foo

要查看什么是正确的方法，您可以使用以下命令查看 Django 如何导入模型：

print models.get_models()

The problem is how you import the classes. Instead of:

from myapp.models import Foo

use:

from myproject.myapp.models import Foo

To see what is the right way, you can see how Django is importing your models with:

print models.get_models()

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酒废 2024-12-19 07:46:57

也许像

subclasses = Foo.__subclasses__()
for subclass in subclasses:
    # we need to keep looking for subclasses of the subclasses
    subclasses += subclass.__subclasses__()
# sometimes we don't care about abstract classes
concrete_subclasses = filter(lambda c: not c._meta.abstract, subclasses)

maybe something like

subclasses = Foo.__subclasses__()
for subclass in subclasses:
    # we need to keep looking for subclasses of the subclasses
    subclasses += subclass.__subclasses__()
# sometimes we don't care about abstract classes
concrete_subclasses = filter(lambda c: not c._meta.abstract, subclasses)

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