3
from django.db import models
class Story(models.Model):
id = models.IntegerField(primary_key=True)
news_type = models.CharField(max_length=255,null=True)
category_id = models.CharField(max_length=255,null=True)
title = models.CharField(max_length=255,null=True)
created = models.DateTimeField(null=True)
author = models.CharField(max_length=255, null=True)
author_title = models.CharField(max_length=255, null=True)
image_caption = models.TextField(null=True)
image_credit = models.CharField(max_length=255,null=True)
image_full_url = models.CharField(max_length=255,null=True)
body = models.TextField(null=True)
summary = models.TextField(null=True)
video_id = models.CharField(max_length=255,null=True)
external_url = models.CharField(max_length=255,null=True)
order = models.IntegerField(null=True)
class StoryFactBox(models.Model):
story = models.ForeignKey('Story', null = True)
body = models.TextField()
class StoryKeyword(models.Model):
story = models.ForeignKey('Story', null = True)
keyword = models.CharField(max_length=255)
models.ForeignKey('Story', null = True)
会导致什么模式更改?django ForeignKey null = true
我从文档阅读:
我想用remove()方法和明确的(),这是文件的一部分。
为了防止数据库不一致,该方法只存在于ForeignKey对象,其中null = True。如果相关字段不能设置为无(NULL),则不能将对象从关系中删除而不添加到另一个。在上面的例子中,从b.entry_set()中删除e相当于做e.blog = None,并且因为博客ForeignKey没有null = True,所以这是无效的。