gistfile1.py

class User(models.Model):

    login = models.CharField(max_length=64)

    @property
    def info(self):
        return UserInfo.objects.get_or_create(user=self)[0]

class UserInfo(models.Model):

    name = models.CharField(max_length=64)

    def update(self, **fields):
        for k, v in fields.items():
            setattr(self, k, v)
        self.save()



user = User.objects.create(login='foo')
user.info.update(name='bar')

print user.info.name  # result: 'bar'