【Python】django报错：TypeError: __init__() missing 1 required positional argument: 'on

错误代码：

from __future__ import unicode_literals
from django.db import models
from django.utils.encoding import python_2_unicode_compatible@python_2_unicode_compatible
class Author(models.Model):name = models.CharField(max_length=50)qq = models.CharField(max_length=10)addr = models.TextField()email = models.EmailField()def __str__(self):return self.name@python_2_unicode_compatible
class Article(models.Model):title = models.CharField(max_length=50)author = models.ForeignKey(Author)content = models.TextField()score = models.IntegerField()tags = models.ManyToManyField('Tag')

报错信息：

D:\PythonWorkstation\django\django_station\queryset>python manage.py makemigrations
Traceback (most recent call last):
部分省略.....
class Article(models.Model):
File "D:\PythonWorkstation\django\django_station\queryset\blog\models.py", line 20, in Article
author = models.ForeignKey('Author')
TypeError: __init__() missing 1 required positional argument: 'on_delete'

原因解读：

在django2.0后，定义外键和一对一关系的时候需要加on_delete选项，此参数为了避免两个表里的数据不一致问题，否则就会报错：TypeError: __init__() missing 1 required positional argument: 'on_delete'

错误代码块：

author = models.ForeignKey(Author)

更正后：

author = models.ForeignKey(Author,on_delete=models.CASCADE)

再次执行更正后的代码即正常

D:\PythonWorkstation\django\django_station\queryset>python manage.py makemigrations
Migrations for 'blog':
blog\migrations\0001_initial.py
- Create model Article
- Create model Author
- Create model Tag
- Add field author to article
- Add field tags to article

对on_delete参数的说明：
on_delete有CASCADE、PROTECT、SET_NULL、SET_DEFAULT、SET()五个参数：
CASCADE：此值设置，是级联删除；
PROTECT：此值设置，是会报完整性错误；
SET_NULL：此值设置，会把外键设置为null，前提是允许为null；
SET_DEFAULT：此值设置，会把设置为外键的默认值；
SET()：此值设置，会调用外面的值，可以是一个函数。
一般情况下使用CASCADE就可以了。

【Python】django报错：TypeError: init() missing 1 required positional argument: 'on_delete'解决办法相关推荐

django报错TypeError: __init__() missing 1 required positional argument: 'on_delete'
个人博客页面链接:http://www.shihao.online (django搭建的个人博客,还在完善中) django报错 TypeError: __init__() missing 1 req ...
TypeError: __init__() missing 1 required positional argument: 'on_delete' 解决办法
Django 中创建Model时报以下错误: TypeError: init() missing 1 required positional argument: 'on_delete' 代码如下: f ...
Django报错：__init__() missing 1 required positional argument: 'on_delete'
1. 问题在根据models生成数据库表时,Django报__init__() missing 1 required positional argument: 'on_delete' 源代码如下: ...
Django 生成数据库表时的报错TypeError: __init__() missing 1 required positional argument: 'on_delete'...
原因及解决办法: https://www.cnblogs.com/phyger/p/8035253.html 转载于:https://www.cnblogs.com/yun1108/p/9197195 ...
PyCharm 添加外键的时候报错 TypeError:__init__()missing 1 required positional argument:‘on_delete‘
主要是 Django 版本问题,由2.0 后就需要添加上这一块的信息. 在对应的对象外键 ,例如: class Comment(models.Model):content = models.Text ...
Django关联数据库时报错TypeError: __init__() missing 1 required positional argument: 'on_delete'...
sgrade = models.ForeignKey("Grades",) 执行python manage.py makemigrations后出现 TypeError: __in ...
解决Django: [TypeError: __init__() missing 1 required positional argument: 'on_delete']
试用python3.7 + Django2.1.3的时候, 在创建模型类关联外键时, 报如下错误: Traceback (most recent call last):xxxxxxxxxxx Type ...
Django:TypeError: __init__() missing 1 required positional argument: 'on_delete'
在Django框架中,有表与表间的关联时,使用命令:python manage.py makmigrations models中的创建表的代码: class Book(models.Model):na ...
Django - TypeError: __init__() missing 1 required positional argument: ‘on_delete‘ 的解决办法
Django 中创建Model时报以下错误: TypeError: init() missing 1 required positional argument: 'on_delete' 代码如下: f ...

【Python】django报错：TypeError: init() missing 1 required positional argument: 'on_delete'解决办法

【Python】django报错：TypeError: init() missing 1 required positional argument: 'on_delete'解决办法相关推荐

最新文章

热门文章

【Python】django报错：TypeError: __init__() missing 1 required positional argument: 'on_delete'解决办法

【Python】django报错：TypeError: __init__() missing 1 required positional argument: 'on_delete'解决办法相关推荐

最新文章

热门文章

【Python】django报错：TypeError: init() missing 1 required positional argument: 'on_delete'解决办法

【Python】django报错：TypeError: init() missing 1 required positional argument: 'on_delete'解决办法相关推荐