使用sqlalchemy的时候

[ltzliwe]

from flaskext.sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///models.db'

db = SQLAlchemy() #把这两行换成 db = SQLAlchemy(app)就正确了
db.init_app(app)

class Role(db.Model):
...

有这样的错误。。 为什么呢
raise RuntimeError('application not registered on db '
RuntimeError: application not registered on db instance and no application bound to current context

[swcsend]

可以参考这个 StackOverflow 的回答
https://stackoverflow.com/questions/19437883/when-scattering-flask-models-runtimeerror-application-not-registered-on-db-w/19438054#19438054

简单说就是和 flask 的 app context 有关系