python - Internal Server Error when using Flask session

Question

I want to save an ID between requests, using Flask session cookie, but I'm getting an Internal Server Error as result, when I perform a request.

I prototyped a simple Flask app for demonstrating my problem:

#!/usr/bin/env python

from flask import Flask, session

app = Flask(__name__)

@app.route('/')
def run():
    session['tmp'] = 43
    return '43'

if __name__ == '__main__':
    app.run()

Why I can't store the session cookie with the following value when I perform the request?

Answer 1

According to Flask sessions documentation:

... What this means is that the user could look at the contents of your cookie but not modify it, unless they know the secret key used for signing.

In order to use sessions you have to set a secret key.

Set secret key. And you should return string, not int.

#!/usr/bin/env python

from flask import Flask, session

app = Flask(__name__)

@app.route('/')
def run():
    session['tmp'] = 43
    return '43'

if __name__ == '__main__':
    app.secret_key = 'A0Zr98j/3yX R~XHH!jmN]LWX/,?RT'
    app.run()