django2.0

from django.db import models

class UserInfo(models.Model):
    user = models.CharField(max_length=32)
    pwd = models.CharField(max_length=32)

class Token(models.Model):
    user = models.OneToOneField(UserInfo,on_delete=None)
    token = models.CharField(max_length=64)

# 关键字on_delete=None
# 2.0版本在源码中取消了on_delete=None，需要手动传递，

class OneToOneField(ForeignKey):

    def __init__(self, to, on_delete, to_field=None, **kwargs): # 源码中取消默认值
        kwargs[‘unique‘] = True
        super().__init__(to, on_delete, to_field=to_field, **kwargs)


# 而在django1.11.5和1.8.17版本中，都是有默值的
def __init__(self, to, on_delete=None, to_field=None, **kwargs):