Cross-referencing foreign keys in Django 1.4

问题

I have a Django project where I would need two models to have a foreign key to each other. However this is not possible because two Python files would have to import each other which Python doesn't allow. What is the best way to solve this problem?

So my code currently looks like this:

countries/models.py:

from django.db.models import Model, ForeignKey
from users.models import Profile

class Country(Model):
    president = ForeignKey(Profile)

users/models.py:

from django.db.models import Model, ForeignKey
from countries.models import Country

class Profile(Model):
    citizenship = ForeignKey(Country)

Error given is: ImportError: cannot import name Profile

回答1:

You can write referenced models as string:

users/models.py:

from django.db.models import Model, ForeignKey

class Profile(Model):
    citizenship = ForeignKey('countries.Country')

来源：https://stackoverflow.com/questions/16263219/cross-referencing-foreign-keys-in-django-1-4