python - 使用 Flask-Session 扩展，未在 flask session 中设置 key

Question

现在我正在使用 flask 3rd 方库 Flask-Session而且我没有运气让 session 正常工作。

当我连接到我的网站时，我收到以下错误:

RuntimeError: the session is unavailable because no secret key was set. Set the secret_key on the application to something unique and secret.

下面是我的服务器代码。

from flask import Flask, session
from flask.ext.session import Session

SESSION_TYPE = 'memcache'
    
app = Flask(__name__)
sess = Session()

nextId = 0

def verifySessionId():
    global nextId

    if not 'userId' in session:
        session['userId'] = nextId
        nextId += 1
        sessionId = session['userId']
        print ("set userid[" + str(session['userId']) + "]")
    else:
        print ("using already set userid[" + str(session['userId']) + "]")
    sessionId = session.get('userId', None)
    return sessionId

@app.route("/")
def hello():
    userId = verifySessionId()
    print("User id[" + str(userId) + "]")
    return str(userId)

if __name__ == "__main__":
    app.secret_key = 'super secret key'

    sess.init_app(app)

    app.debug = True
    app.run()

如您所见，我确实设置了应用程序 key 。我做错了什么？

还有其他 session 选项吗？

其他信息: 在 Linux Mint 上运行 Python 2.7

完整粘贴:

Traceback (most recent call last):
  File "/home/sean/code/misc/hangman/venv/lib/python2.7/site-packages/flask/app.py", line 1836, in __call__
    return self.wsgi_app(environ, start_response)
  File "/home/sean/code/misc/hangman/venv/lib/python2.7/site-packages/flask/app.py", line 1820, in wsgi_app
    response = self.make_response(self.handle_exception(e))
  File "/home/sean/code/misc/hangman/venv/lib/python2.7/site-packages/flask/app.py", line 1403, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/home/sean/code/misc/hangman/venv/lib/python2.7/site-packages/flask/app.py", line 1817, in wsgi_app
    response = self.full_dispatch_request()
  File "/home/sean/code/misc/hangman/venv/lib/python2.7/site-packages/flask/app.py", line 1477, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/home/sean/code/misc/hangman/venv/lib/python2.7/site-packages/flask/app.py", line 1381, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/home/sean/code/misc/hangman/venv/lib/python2.7/site-packages/flask/app.py", line 1475, in full_dispatch_request
    rv = self.dispatch_request()
  File "/home/sean/code/misc/hangman/venv/lib/python2.7/site-packages/flask/app.py", line 1461, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/home/sean/code/misc/session/sessiontest.py", line 27, in hello
    userId = verifySessionId()
  File "/home/sean/code/misc/session/sessiontest.py", line 16, in verifySessionId
    session['userId'] = nextId
  File "/home/sean/code/misc/hangman/venv/lib/python2.7/site-packages/werkzeug/local.py", line 341, in __setitem__
    self._get_current_object()[key] = value
  File "/home/sean/code/misc/hangman/venv/lib/python2.7/site-packages/flask/sessions.py", line 126, in _fail
    raise RuntimeError('the session is unavailable because no secret '
RuntimeError: the session is unavailable because no secret key was set.  Set the secret_key on the application to something unique and secret.

Answer 1

在您的情况下，NullSessionInterface session 实现引发了异常，这是您使用 Flask-Session 时的默认 session 类型。那是因为您实际上从未将 SESSION_TYPE 配置 提供给 Flask；在您的模块中将其设置为全局是不够。 Flask-Session quickstart example code确实设置了一个全局，但随后通过调用 app.config.from_object(__name__) 将当前模块用作配置对象。

这个默认值对于 Flask 0.10 或更高版本没有多大意义； NullSession 可能对 Flask 0.8 或 0.9 有意义，但在当前版本中 flask.session.NullSession class用作错误信号。在您的情况下，它现在会给您错误的错误消息。

将 SESSION_TYPE 配置选项设置为其他值。选择 redis、memcached、filesystem 或 mongodb 之一，并确保在 app 中进行设置.config(直接或通过 various Config.from_* methods )。

为了快速测试，将其设置为 filesystem 是最简单的；那里有足够的默认配置可以在没有额外依赖项的情况下工作:

if __name__ == "__main__":
    # Quick test configuration. Please use proper Flask configuration options
    # in production settings, and use a separate file or environment variables
    # to manage the secret key!
    app.secret_key = 'super secret key'
    app.config['SESSION_TYPE'] = 'filesystem'

    sess.init_app(app)

    app.debug = True
    app.run()

如果您看到此错误并且您没有使用 Flask-Session，则说明设置密码有问题。如果您在 if __name__ == "__main__": 像上面一样设置 app.config['SECRET_KEY'] 或 app.secret_key并且您收到此错误，那么您可能正在通过 WSGI 服务器运行您的 Flask 应用程序，该服务器将您的 Flask 项目作为模块导入，并且 __name__ == "__main__" block 永远不会运行。

manage configuration for Flask apps in a separate file 总是更好，无论如何。