Django 模型，循环外键

Question

如何建模以下关系:

class Country(models.Model):
  # The capital city of this country
  capital = models.ForeignKey(City)
  ## other country stuff

class City(models.Model):
  # The country where this city lies in
  country = models.ForeignKey(Country)
  ## other city stuff

这显然不能编译。
(城市在国家的定义中是未定义的)。
有什么建议？

Answer 1

您可以使用字符串而不是模型类来引用模型:

class Country(models.Model):
  # The capital city of this country
  capital = models.ForeignKey('City', related_name='+')
  ## other country stuff

另见:

Django models.py Circular Foreign Key

Cross-referencing foreign keys in Django 1.4