Question 213495 in Javascript Question posted in
A very good W3school tutorial can be found here.

Javascript – Flask is not keeping the session

I’m trying to use flask to create a backend for a website

flask doesn’t keep the seasion when the user moves into another page, I tried every single solution from the first 10 pages of google search.

this is my backend (removed unrelevant functions and code)

from flask import Flask, request, jsonify, make_response, session,redirect, url_for
from flask_cors import CORS, cross_origin
import logging
import sqlite3

app = Flask(__name__,template_folder="../templates", static_folder="../static")
logging.basicConfig(level=logging.DEBUG)

CORS(app, resources={r"/*": {"origins": "*"}}, supports_credentials=True)
app.secret_key = "166"  #don't look!!!
app.config.update(SESSION_COOKIE_SAMESITE=None, SESSION_COOKIE_SECURE=True)


# get the user info example
def get_user(username):
    connection = sqlite3.connect('users.db')
    cursor = connection.cursor()
    cursor.execute('SELECT * FROM users WHERE username = ?', (username,))
    user = cursor.fetchone()
    connection.close()
    return user

# get the current user from the seasion
@app.route('/get_current_user', methods=['GET'])
@cross_origin(supports_credentials=True)
def get_current_user():
    if "username" in session:
        return session["username"]
    else:
        return "not logged in"



    return True
@app.route('/register', methods=['POST'])
@cross_origin(supports_credentials=True)
def register():
    data = request.form
    username = data['username']
    password = data['password']
  
   .....

    # Check if the user already exists
    # Add the user to the DB
    # Create a session for the user after successful registration
    session['username'] = username
    session.permanent = True
  ....

    return response

if __name__ == '__main__':
    create_database()
    app.run(debug=True,port=1661,host='0.0.0.0')

as you can see, I added the SESSION_COOKIE_SAMESITE="None", SESSION_COOKIE_SECURE configs, and I use supports_credentials=True everywhere. yet it doesn’t work.

I also did not forget to use the credentials in the js.

    fetch('http://xx.xx.xx.xx:1661/get_current_user', {credentials: 'include'})
      .then(response => response.text())
      .then(username => {
        // Update the content of #user-name with the retrieved username
        const userNameElement = document.getElementById('user-name');
        userNameElement.textContent = username;
      })
      .catch(error => {
        console.error('Error fetching user data:', error);
        // Handle the error if needed
      });

what happnes is that the user registers using /register, it the session is created, and then the user gets redirected using js herf to /user, in this page the user’s client sents a get request to get the username from the server using /get_current_user and the code gets to the "return "not logged in" part. No errors. I’m out of idea.

Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    Answering my own question after soooo much troubleshooitng.

    What I assume was the issue is that the browser didn't sent the cookie because it was cross-domain (different ports) without htpps.

    If I unserstand correctly, there is no way to make it work without either enabling https or avoiding cross-domain requests.

    I chose to avoid cross-domain requests by making everything run from the flask server.


  2. 0

    Try this…

    change the session["username"] to session.get("username")

    def get_current_user():
    if "username" in session:
        return session.get("username")
    else:
        return "not logged in"
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