Question

我目前正在编写Corey Schafer编写的Python Flask教程。在蓝图视频中，我在导出变量时遇到了麻烦。我已经写过~/.bash_profile和~/.profile了，但是没有成功。

在我的.profile文件中：

export SECRET_KEY='5791628bb0b13ce0c676dfde280ba245'
export SQLALCHEMY_DATABASE_URI='sqlite:///sitetest.db'
export EMAIL_USER='email'
export EMAIL_PASS='password'

在我的config.py文件中：

import os

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

在我的 init .py文件中

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 flaskblog.config import Config

app = Flask(__name__)
app.config.from_object(Config)
db = SQLAlchemy(app)
bcrypt = Bcrypt(app)
login_manager= LoginManager(app)
login_manager.login_view = 'users.login'
login_manager.login_message_category = 'info'

mail = Mail(app)

from flaskblog.users.routes import users
from flaskblog.posts.routes import posts
from flaskblog.main.routes import main

app.register_blueprint(users)
app.register_blueprint(posts)
app.register_blueprint(main)

我已经弄清楚，很可能没有导出变量。有什么建议吗？

Traceback (most recent call last):
  File "/home/michael/anaconda3/lib/python3.7/site-packages/flask/app.py", line 2309, in __call__
    return self.wsgi_app(environ, start_response)
  File "/home/michael/anaconda3/lib/python3.7/site-packages/flask/app.py", line 2295, in wsgi_app
    response = self.handle_exception(e)
  File "/home/michael/anaconda3/lib/python3.7/site-packages/flask/app.py", line 1741, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/home/michael/anaconda3/lib/python3.7/site-packages/flask/_compat.py", line 35, in reraise
    raise value
  File "/home/michael/anaconda3/lib/python3.7/site-packages/flask/app.py", line 2292, in wsgi_app
    response = self.full_dispatch_request()
  File "/home/michael/anaconda3/lib/python3.7/site-packages/flask/app.py", line 1815, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/home/michael/anaconda3/lib/python3.7/site-packages/flask/app.py", line 1718, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/home/michael/anaconda3/lib/python3.7/site-packages/flask/_compat.py", line 35, in reraise
    raise value
  File "/home/michael/anaconda3/lib/python3.7/site-packages/flask/app.py", line 1813, in full_dispatch_request
    rv = self.dispatch_request()
  File "/home/michael/anaconda3/lib/python3.7/site-packages/flask/app.py", line 1799, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/home/michael/Flask_Blog/flaskblog/main/routes.py", line 11, in home
    posts = Post.query.order_by(Post.date_posted.desc()).paginate(page=page, per_page=5)
  File "/home/michael/anaconda3/lib/python3.7/site-packages/flask_sqlalchemy/__init__.py", line 519, in __get__
    return type.query_class(mapper, session=self.sa.session())
  File "/home/michael/anaconda3/lib/python3.7/site-packages/sqlalchemy/orm/scoping.py", line 78, in __call__
    return self.registry()
  File "/home/michael/anaconda3/lib/python3.7/site-packages/sqlalchemy/util/_collections.py", line 1012, in __call__
    return self.registry.setdefault(key, self.createfunc())
  File "/home/michael/anaconda3/lib/python3.7/site-packages/sqlalchemy/orm/session.py", line 3206, in __call__
    return self.class_(**local_kw)
  File "/home/michael/anaconda3/lib/python3.7/site-packages/flask_sqlalchemy/__init__.py", line 138, in __init__
    bind = options.pop('bind', None) or db.engine
  File "/home/michael/anaconda3/lib/python3.7/site-packages/flask_sqlalchemy/__init__.py", line 937, in engine
    return self.get_engine()
  File "/home/michael/anaconda3/lib/python3.7/site-packages/flask_sqlalchemy/__init__.py", line 956, in get_engine
    return connector.get_engine()
  File "/home/michael/anaconda3/lib/python3.7/site-packages/flask_sqlalchemy/__init__.py", line 560, in get_engine
    options = self.get_options(sa_url, echo)
  File "/home/michael/anaconda3/lib/python3.7/site-packages/flask_sqlalchemy/__init__.py", line 575, in get_options
    self._sa.apply_driver_hacks(self._app, sa_url, options)
  File "/home/michael/anaconda3/lib/python3.7/site-packages/flask_sqlalchemy/__init__.py", line 877, in apply_driver_hacks
    if sa_url.drivername.startswith('mysql'):
AttributeError: 'NoneType' object has no attribute 'drivername'

Answer 1

您是否在烧瓶项目中使用虚拟环境 ？下面的解决方案只适合您。

因此，当您使用虚拟环境时，它会以不同的安装软件包特权在自己的环境中工作。同样适用于环境变量。当您在bash_profile中添加环境变量并运行项目（使用虚拟环境）时，根本找不到这些变量。解决方法是..

在虚拟环境路径中创建自己的变量文件（例如， var_file ；如下所示） 。请参阅 terminal 中的以下命令，以获取更清晰的说明。

> vim ~/.virtualenvs/your_project_virtual_environment_name/bin/var_file

此处将打开外壳文件

# add your environment variables
export abc='xyz'
export xyz='wtf'

现在退出文件（esc +：+ wq！）


> source ~/.virtualenvs/your_project_virtual_environment_name/bin/new_shell_file

Voila .. !!立即尝试运行项目。它应该像蜂蜜一样光滑。让我知道是否有效。：）

Answer 2

您需要为SQLALCHEMY_DATABASE_URI环境变量设置适当的DSN。根据文档，它必须具有有效的方言前缀，例如mysql，postgresql或sqlite：

https://docs.sqlalchemy.org/en/13/core/engines.html#database-urls

sa_url.drivername.startswith('mysql'):

堆栈跟踪中的这一行表示您提供的DSN最有可能缺少驱动程序名称。

确保os.environ.get('SQLALCHEMY_DATABASE_URI')返回有效的DSN。

Answer 3

我正在阅读同一教程，并且对此也做了一些努力。

我尝试添加assert语句以查看哪个环境变量返回None。 SECRET_KEY和DATABASE_URI都给我带来麻烦。我尝试更改变量名称，甚至删除引号。

我不太确定哪个更改可以解决问题，但是我可以通过重新启动终端使环境变量正常工作。

我希望这对以后的人有帮助。

AttributeError：'NoneType'对象没有Flask Web App的属性'drivername'

3 个答案: