【解决方案】You are trying to add a non-nullable field 'content' to blog without a default;

网页报错
/ admin / blog / blog / add /中的OperationalError

>python manage.py makemigrations
You are trying to add a non-nullable field 'price_monthly' to product without a default; we can't do that (the database needs something to populate existing rows).
Please select a fix:
 1) Provide a one-off default now (will be set on all existing rows)
 2) Quit, and let me add a default in models.py
Select an option:

这个可能是之前已创建了表中的一条记录，之后模型中增加了一个非空的字段，但是原来已经存在的记录没有这个值

解决方案：

在基类b中添加允许为空或者添加默认值，并设置b不建表（meta中的abstract = true

class Blog(models.Model):
	"""docstring for blog"""
	title=models.CharField(max_length=50)
	blog_type=models.ForeignKey(BlogType,on_delete=models.DO_NOTHING)
	content=RichTextUploadingField(null=True)
	auther=models.ForeignKey(User,on_delete=models.DO_NOTHING)
	create_time=models.DateTimeField(auto_now_add=True)
	last_updated_time=models.DateTimeField(auto_now=True)

还有一招直接删库重来