在Python中转发类声明 [英] Forward class declaration in Python

问题描述

我有两个课程：

class A(models):
    ...

class B(models):
    a = models.ManyToManyField(A)

现在我必须将我的模型更改为以下：

Now I have to change my model to one below:

class A(models):
    b = models.ManyToManyField(B)

class B(models):
    ...

我必须使用南移。我想在A类中创建新的多对多字段，从B类迁移数据和删除字段。问题是两者都在同一模型中。所以当我把很多到很多的A类，这是不能被看到的。因为B声明低于A.如何解决这个问题？

I have to use south migrations. I wanted to create new many to many field in class A, migrate data and delete field from class B. The problem is that both are in same model. So when I put many to many into A class it cannot be seen. Because B declaration is below A. How to solve this problem?

推荐答案

至少SQLAlchemy允许您使用字符串而不是类。尝试如果django-orm也允许。

At least SQLAlchemy allows you to use a string instead of a class. Try if django-orm allows that, too.

a = models.ManyToManyField('A')
# ...
b = models.ManyToManyField('B')

更新：根据 Django / Python循环模型参考完全可以走。

Update: According to Django/Python Circular model reference that's exactly the way to go.

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