从 RDS 检索数据给出 AttributeError: 'sqlalchemy.cimmutabledict.immutabledict' object has no attribute 'setdefault' [英] Retrieving data from RDS gives AttributeError: 'sqlalchemy.cimmutabledict.immutabledict' object has no attribute 'setdefault'

问题描述

每当调用 API 端点 {{url}}/api/users/login 对用户进行身份验证时，我都想从 RDS 检索用户数据，但是，我目前在检索数据时遇到问题来自 RDS.

I would like to retrieve user data from RDS whenever the API endpoint {{url}}/api/users/login is called to authenticate users, however, I am currently having issues with retrieving data from RDS.

这是错误的完整堆栈跟踪:

This is the full stacktrace of the error:

Flask==1.1.2
Flask-Cors==3.0.10
flask-marshmallow==0.14.0
Flask-Migrate==2.5.3
Flask-RESTful==0.3.8
Flask-SQLAlchemy==2.4.4
marshmallow==3.10.0
marshmallow-sqlalchemy==0.24.1
SQLAlchemy==1.4.0b1
python==3.7

我解决问题的尝试

我尝试解决问题但无济于事的一些事情是:

My attempts to solve the problem

Some things that I've attempted to resolve the issue but to no avail are:

• 使用 pymysql 连接器代替 mysqlconnector
• 降级烧瓶棉花糖==0.11.0
• 降级棉花糖==3.6.1
• 降级棉花糖-sqlalchemy==0.23.1

我已经对我的应用程序进行了 Docker 化，这是我当前的设置:

I have Dockerized my application and this is my current set up:

app.py

from flask_marshmallow import Marshmallow
from flask_migrate import Migrate
from flask_sqlalchemy import SQLAlchemy
from flask_jwt_extended import JWTManager

db = SQLAlchemy()
ma = Marshmallow()
migrate = Migrate()

def register_extensions(app: Flask) -> None:
   db.init_app(app)
   migrate.init_app(app, db)
   ma.init_app(app)

def create_application() -> Flask:
   app: Flask = Flask(__name__)
   app.config['SQLALCHEMY_DATABASE_URI'] = "mysql+mysqlconnector://{DB_USER}:{DB_PASSWORD}@{DB_INSTANCE}:{DB_PORT}"
   app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
   register_extensions(app)
   app.register_blueprint(users_urls.mod, url_prefix=f"/{BEP_PREFIX}/users")

   return app

 app = create_application()
 CORS(app)

models.py

class Accounts(db.Model):
    __tablename__ = 'Accounts'
    username = db.Column(db.String(100), primary_key=True)
    password = db.Column(db.String(256), nullable=False)
    email = db.Column(db.String(255), nullable=False)
    personnelID = db.Column(db.String(255), nullable=False)
    userType = db.Column(db.String(45), nullable=False)

service.py

class UserService(Service):
    __model__ = Accounts

    def get(self, username):
        return Accounts.query.filter_by(username=username).first()

user_service = UserService()

views.py

from bep.users.services import user_service

class UserLogin(Resource):
   def post(self):
       data = request.get_json()

       try:
           userData = user_service.get("test")
       except Exception:
           error_str = traceback.format_exc()
           logger.error("This prints the stack", exc_info=True)
           return UserServiceError.to_response(error=error_str, comments="Something went wrong while logging in") 

推荐答案

问题出在 flask-sqlalchemy 中的已知问题，由 SQLAchemy 1.4 中的更改引起.Flask-sqlalchemy 尝试修改 SQLALchemy 引擎的 URL，但这些 URL 在 SQLAlchemy 1.4 中是不可变的.

The problem is a known issue in flask-sqlalchemy, caused by changes in SQLAchemy 1.4. Flask-sqlalchemy attempts to modify the SQLALchemy engine's URL, but these URLs are immutable in SQLAlchemy 1.4.

该问题已在 Flask-SQLAlchemy 2.5+ (更改日志).

The problem is fixed in Flask-SQLAlchemy 2.5+ (changelog).

如果无法升级 Flask-SQLAlchemy，可以通过指定传递给 pip 的 SQLAlchemy 版本来解决该问题，或者通过命令行

If upgrading Flask-SQLAlchemy is not possible, the issue can be worked around by specifying the SQLAlchemy version passed to pip, either via the command line

pip install --upgrade 'SQLAlchemy<1.4'

或在 requirements.txt 中

or in requirements.txt

SQLAlchemy<1.4

SQLAlchemy 1.4 于 2021 年 3 月 15 日正式发布.

SQLAlchemy 1.4 went on general release on 15 March 2021.

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