Flask session variables

Question

I'm writing a small web app with flask. I have a problem with session variables when two users (under the same network) try to use app.

This is the code:

import os

from flask import Flask, request, render_template, g, session
from random import randint

def random():
     session['number'] = randint(0,4)
     return None

@app.route('/')
def home():
  if not session.get('logged_in'):
    return render_template('login.html')
  else: 
    return check()

@app.route('/login', methods = ['GET', 'POST'])
def login():
      global username
      username = request.form['username']
      session['logged_in'] = True
      session['username'] = username
      return check()

@app.route('/check', methods=['GET', 'POST'])
def check():
       random()
       return render_template('file.html', number = session['number'], user = session['username'])

if __name__ == "__main__":
    app.secret_key = ".."
    app.run(host = '0.0.0.0',port = 3134, debug=False)

In file.html there is a button type "submit" that call '/check' route. The problem is when two users use app at same time because the variable 'number' is equal to variable 'number' of the last user that push the button... there isn't indipendence between two sessions.

I would that the two users has two indipendence sessions, like if they use my app in local host.

Answer 1

Using randint(0,4) to generate number means that they will sometimes be equal for different users. To generate unique number every time use uuid:

from uuid import uuid4
def random():
    session['number'] = str(uuid4())
    return None

or generator:

import itertools
consequent_integers = itertools.count()

def random():
    session['number'] = consequent_integers.next()
    return None