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AttributeError:'NoneType' object没有属性'drivername'

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我启动应用程序时出现此错误 . 显然它与SQLAlchemy有关 . 在Corey Schaffer Flask教程的帮助下,我一直在使用这个例子 .

> File "C:\Users\Matea\venv\lib\site-packages\flask\app.py", line 2309, in __call__
return self.wsgi_app(environ, start_response)
File "C:\Users\Matea\venv\lib\site-packages\flask\app.py", line 2295, in wsgi_app
response = self.handle_exception(e)
File "C:\Users\Matea\venv\lib\site-packages\flask\app.py", line 1741, in handle_exception
reraise(exc_type, exc_value, tb)
File "C:\Users\Matea\venv\lib\site-packages\flask\_compat.py", line 35, in reraise
raise value
File "C:\Users\Matea\venv\lib\site-packages\flask\app.py", line 2292, in wsgi_app
response = self.full_dispatch_request()
File "C:\Users\Matea\venv\lib\site-packages\flask\app.py", line 1815, in full_dispatch_request
rv = self.handle_user_exception(e)
File "C:\Users\Matea\venv\lib\site-packages\flask\app.py", line 1718, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "C:\Users\Matea\venv\lib\site-packages\flask\_compat.py", line 35, in reraise
raise value
File "C:\Users\Matea\venv\lib\site-packages\flask\app.py", line 1813, in full_dispatch_request
rv = self.dispatch_request()
File "C:\Users\Matea\venv\lib\site-packages\flask\app.py", line 1799, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "C:\Users\Matea\myblog\myblog\main\routes.py", line 11, in home
posts = Post.query.order_by(Post.date_posted.desc()).paginate(page=page, per_page=5)
File "C:\Users\Matea\venv\lib\site-packages\flask_sqlalchemy\__init__.py", line 514, in __get__
return type.query_class(mapper, session=self.sa.session())
File "C:\Users\Matea\venv\lib\site-packages\sqlalchemy\orm\scoping.py", line 74, in __call__
return self.registry()
File "C:\Users\Matea\venv\lib\site-packages\sqlalchemy\util\_collections.py", line 1001, in __call__
return self.registry.setdefault(key, self.createfunc())
File "C:\Users\Matea\venv\lib\site-packages\sqlalchemy\orm\session.py", line 2950, in __call__
return self.class_(**local_kw)
File "C:\Users\Matea\venv\lib\site-packages\flask_sqlalchemy\__init__.py", line 143, in __init__
bind = options.pop('bind', None) or db.engine
File "C:\Users\Matea\venv\lib\site-packages\flask_sqlalchemy\__init__.py", line 877, in engine
return self.get_engine()
File "C:\Users\Matea\venv\lib\site-packages\flask_sqlalchemy\__init__.py", line 896, in get_engine
return connector.get_engine()
File "C:\Users\Matea\venv\lib\site-packages\flask_sqlalchemy\__init__.py", line 556, in get_engine
self._sa.apply_driver_hacks(self._app, info, options)
File "C:\Users\Matea\venv\lib\site-packages\flask_sqlalchemy\__init__.py", line 830, in apply_driver_hacks
if info.drivername.startswith('mysql'):
AttributeError: 'NoneType' object has no attribute 'drivername'

这是一些代码:这是来自我的 init .py

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_bcrypt import Bcrypt
from flask_login import LoginManager
from flask_mail import Mail
from myblog.config import Config


db = SQLAlchemy()
bcrypt = Bcrypt()
login_manager = LoginManager()
login_manager.login_view = 'users.login'
login_manager.login_message_category = 'info'
mail = Mail()


def create_app(config_class=Config):
    app = Flask(__name__)
    app.config.from_object(Config)

    db.init_app(app)
    bcrypt.init_app(app)
    login_manager.init_app(app)
    mail.init_app(app)

    from myblog.users.routes import users
    from myblog.posts.routes import posts
    from myblog.main.routes import main
    from myblog.errors.handlers import errors
    app.register_blueprint(users)
    app.register_blueprint(posts)
    app.register_blueprint(main)
    app.register_blueprint(errors)

    return app

这段代码来自config.py

import os


class Config:
    SECRET_KEY = os.environ.get('SECRET_KEY')
    SQLALCHEMY_DATABASE_URI = os.environ.get('SQLALCHEMY_DATABASE_URL')
    MAIL_SERVER = 'smtp.googlemail.com'
    MAIL_PORT = 587
    MAIL_USE_TLS = True
    MAIL_USERNAME = os.environ.get('EMAIL_USER')
    MAIL_PASSWORD = os.environ.get('EMAIL_PASS')

我希望你能帮助我,如果遗漏了什么,请告诉我,谢谢!

3 回答

  • 1

    如果你在 .bash_proflie 中正确设置了环境变量

    export EMAIL_USER='youremail@gmail.com'
        export EMAIL_PASS='Yourpassword'
        export SQLALCHEMY_DATABASE_URI='sqlite:///site.db'
        export SECRET_KEY='secretkeyxxxxxxxxxxxxxxxx'
    

    然后尝试重新启动计算机 .
    如果它仍然失败尝试在python中创建数据库

    from your yourflaskapp import db
    db.create_all()
    

    如果您的应用是蓝图

    use from yourapp import create_app
        app = create_app()
        app.app_context().push()
    

    进行更改后,请始终刷新文本编辑器和终端 . 还要尝试确保您在正确的目录中运行您的应用程序 .

    欲了解更多信息,请访问蓝图使用

    http://flask-sqlalchemy.pocoo.org/2.3/contexts/

  • 0

    问题是你没有将 app 传递给 SQLAlchemy ;应该这样做 . 但通常该错误意味着您的数据库连接未定义或您没有相应的数据库驱动程序集 .

    试试这个:

    app = Flask(__name__)
    app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:////tmp/test.db'
    db = SQLAlchemy(app)
    
  • 0

    @Ivan M,我正在阅读相同的教程并且也遇到了这个问题 . 发生这种情况是因为讲师将数据库URI和其他参数移动到环境变量中(请参阅Part 11约27分钟) . 这是一项安全措施和良好的开发实践 .
    为了使配置文件正常工作,请还原init.py中的更改并更新config.py以使用直接链接而不是方括号:
    SQLALCHEMY_DATABASE_URI = 'sqlite:///site.db'
    UPD:同样适用于 SECRET_KEY 和其他你希望硬编码的参数:
    SECRET_KEY = '5791628bb0b13ce0c676dfde280ba245'

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