Flask-SQLAlchemy 工程化时，如何避免"The setup method 'shell_context_processor' can no longer be called on the application"错误？

nexpect system error - the setup method 'shell_context_processor' can no longer be called on the application. it has already handled its first request, any changes will not be applied consistently.
make sure all imports, decorators, functions, etc. needed to set up the application are done before running it.

from flask import flask
from flask_sqlalchemy import sqlalchemy

app = flask(__name__)
db = sqlalchemy()

setting = app.config["database"]
app.config["sqlalchemy_database_uri"] = f'mysql+pymysql://{setting["db_user"]}:{setting["db_pass"]@{setting["db_host"]}/{setting["db_name"]}'

db.init_app(app)

from model.user import User
from a import DB, app

class Account:

    @staticmethod
    def login(username, password):
        with app.test_context():
            user = DB.session.execute(DB.select(User).filter_by(name=username)).scalar_one()

        return "token"