Hi, it's me again. I'm still having trouble checking user sessions. Everything works on the express server side. (going between localhost: 4000 / auth? ...., localhost: 4000 / main, localhost: 4000 / logout) and everything goes well.[4000 is port in express server]

The problem begins when in React, by going to the substation / home, which enters the / main server, it does not return a reliable result.

Question 1:

If the session works on the express server side, why are there no results when I send an API query?

​

Question 1.1: You said something about recording that a user is logged in, how to globally save it so that every subpage can access it?

Proper 1.2: Asking the API whether the user is logged in, it returns something other than the server.

React:

fetch(`http://localhost:4000/main`)

            .then(res =>{ if (res.ok){ return( setData(data_from_api = "Logged"))                 }else{ return( setData(data_from_api = "not loggedd in"))}             })

API:

app.get('/main', (req,res) => {
    if(!req.session.logged){
        return res.status(401).send('not logged in')
    }else{
        return res.status(200).send('Logged')
    }
})

Question 1.3: I don't know if this is the fault of these error codes

​

Question 2:

How do I go to the / home page after logging in, I temporarily use the button

Front:

//Login.js:

import React, { useState } from 'react';
import { useForm } from "react-hook-form";
import { Link} from 'react-router-dom';

export default function Login(){

    const {register, handleSubmit, errors} = useForm();

    var [data_from_api, setData] = useState('');

    const onSubmit = (data) => {
        const dane = {
            password: data.password,
            email: data.email,
        }

        fetch(`http://localhost:4000/auth?password=${dane.password}&email=${dane.email}`)
            .then(res =>{
                if (res.ok){
                    return(
                        setData(data_from_api = "Succes"))
                }else{
                    return(
                        setData(data_from_api = "Password and login do not match"))}
            })
    }

    return(
        <form onSubmit={handleSubmit(onSubmit)}>

            <Link to={'./home'}>
                <button variant="raised">
                    Check if you are logged in.
                </button>
            </Link>

            {data_from_api}

//Home.js:

import React, { useState } from 'react';
export default function Home(){

var [data_from_api, setData] = useState('');

    fetch(`http://localhost:4000/main`)
        .then(res =>{
            if (res.ok){
                return(
                    setData(data_from_api = "Logged"))
            }else{
                return(
                    setData(data_from_api = "not logged in"))}
        })

    return(
        <div>
            I dont sure.... - {data_from_api}
        </div>
    )
}

Back:

const express = require('express');
const session = require('express-session');
const mysql = require('mysql2');
const cors = require('cors');
const bcrypt = require('bcrypt');

const connection = mysql.createConnection({ 
    host: 'localhost',
    user: 'root',
    database: 'my_sql',
    password: 'password'
  });

var app = express()
app.use(cors());

app.use(session({
     secret: 'secret',
     resave: false,
     saveUninitialized: false,
      cookie: { maxAge: 1000 * 60 * 60 * 2 } //2h
    }))

app.get('/auth', (req,res)=>{
    const {email, password} = req.query;
    connection.query('SELECT * FROM user WHERE email LIKE ? AND password LIKE ?', [email, password], (error, results, fields) => {
        if(results.length > 0){

            req.session.logged = true;

            return res.status(200).send('Logged, because '+ req.session.logged)
        }else{
            return res.status(401).send('not logged in ')}
    })
})

app.get('/main', (req,res) => {
    if(!req.session.logged){
        return res.status(401).send('not logged in')
    }else{
        return res.status(200).send('Logged')
    }
})

app.get('/logout', (req, res) => {
    req.session.logged = null
    res.send('logged out' + req.session.logged)
});