django访问模型的子类 [英] django accessing subclasses of models

问题描述

我在我的django模型中使用子类，如下所示：

I'm using subclasses in my django-models like this:

class Person(models.Model):
    name = models.CharField(max_length=100)
    ...


class Butcher(Person):
    ...

class Driver(Person):
    ...

在我看来，我想根据Person类的子类
做某些事情，像这样：

In my view i want to do certain things depending on the subclass of the Person-class, like this:

def person_detail_view(request, slug):
    person = Person.objects.get(slug=slug)

    if person.butcher:
        ...

    elif person.driver:
        ...

但是这个给我一个DoesNotExist - 当Person是
驱动。有没有办法向Person类询问其子类？

But this gives me a DoesNotExist-Error when the Person is a Driver. Is there a way to ask the Person class for its subclass?

提前感谢
雅克

Thanks in advance Jacques

推荐答案

你的基本逻辑是健全的;问题在于你如何测试。你必须检查属性的存在，而不是它的价值。例如：

Your basic logic is sound; the problem is in how you're testing. You have to check for the presence of the attribute, not it's value. For example:

def person_detail_view(request, slug):
    person = Person.objects.get(slug=slug)

    if hasattr(person, 'butcher'):
        ...

    elif hasattr(person, 'driver'):
        ...

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