1、产生原因:在创建外键后,执行 python manage.py makemigrations报错,具体代码为:
from django.db import models class Classes(models.Model): title = models.CharField(max_length=32) m = models.ManyToManyField("Teachers") class Teachers(models.Model): name = models.CharField(max_length=32) class Student(models.Model): username = models.CharField(max_length=32) age = models.IntegerField() gender = models.BooleanField() cs = models.ForeignKey("Classes")
2、终端上显示报错为:
D:\pythonstudy\Django_demo>python manage.py makemigrations Traceback (most recent call last): File "manage.py", line 15, in <module> execute_from_command_line(sys.argv) File "C:\Users\huiYan\AppData\Local\Programs\Python\Python36-32\lib\site-packages\django\core\management\__init__.py", line 371, in execute_from_command_line utility.execute() File "C:\Users\huiYan\AppData\Local\Programs\Python\Python36-32\lib\site-packages\django\core\management\__init__.py", line 347, in execute django.setup() File "C:\Users\huiYan\AppData\Local\Programs\Python\Python36-32\lib\site-packages\django\__init__.py", line 24, in setup apps.populate(settings.INSTALLED_APPS) File "C:\Users\huiYan\AppData\Local\Programs\Python\Python36-32\lib\site-packages\django\apps\registry.py", line 112, in populate app_config.import_models() File "C:\Users\huiYan\AppData\Local\Programs\Python\Python36-32\lib\site-packages\django\apps\config.py", line 198, in import_models self.models_module = import_module(models_module_name) File "C:\Users\huiYan\AppData\Local\Programs\Python\Python36-32\lib\importlib\__init__.py", line 126, in import_module return _bootstrap._gcd_import(name[level:], package, level) File "<frozen importlib._bootstrap>", line 978, in _gcd_import File "<frozen importlib._bootstrap>", line 961, in _find_and_load File "<frozen importlib._bootstrap>", line 950, in _find_and_load_unlocked File "<frozen importlib._bootstrap>", line 655, in _load_unlocked File "<frozen importlib._bootstrap_external>", line 678, in exec_module File "<frozen importlib._bootstrap>", line 205, in _call_with_frames_removed File "D:\pythonstudy\Django_demo\app01\models.py", line 18, in <module> class Student(models.Model): File "D:\pythonstudy\Django_demo\app01\models.py", line 22, in Student cs = models.ForeignKey("Classes") TypeError: __init__() missing 1 required positional argument: ‘on_delete‘
3、解决方法:
在外键上后面添加on_delete=models.CASCADE,错误消失。
cs = models.ForeignKey("Classes",on_delete=models.CASCADE,)
Django2.0在根据models生成数据库表时报 __init__() missing 1 required positional argument: 'on_delete'
原文地址:https://www.cnblogs.com/crazyforever/p/9068462.html
时间: 2024-10-10 22:55:33