django models.Model 数据库 添加字段 遇到问题

解决方法:
添加链接描述
https://stackoverflow.com/questions/26185687/you-are-trying-to-add-a-non-nullable-field-new-field-to-userprofile-without-a

models.Model

You are trying to add a non-nullable field ‘aaa’ to post 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 with a null value for this column)
2. Quit, and let me add a default in models.py

You need to provide a default value:

new_field = models.CharField(max_length=140, default=‘SOME STRING’)

rm your_app/migrations/*

rm db.sqlite3
python manage.py makemigrations
python manage.py migrate

ou can’t add reference to table that have already data inside.
Change:

user = models.OneToOneField(User)
to:

user = models.OneToOneField(User, default = “”)
do:

python manage.py makemigrations
python manage.py migrate
change again:

user = models.OneToOneField(User)
do migration again:

python manage.py makemigrations
python manage.py migrate