SessionID is generating a unique value on every post request - node.js

Question

I am trying to identify the user that is on my application via sessionId, not actual info on the user account itself. However, what I am noticing is that the sessionId changes everytime the user performs an action on the page. As shown below. My goal would be to have the same sessionID from the point they open the webpage until they close it.
const app = require('express')();
const https = require('https');
const fs = require('fs');
const session = require('express-session');
function getDateTimestamp(){
var today = new Date();
var date = today.getFullYear()+'_'+(today.getMonth()+1)+'_'+today.getDate();
return date;
}
app.use(session({
resave: false,
saveUninitialized: true,
secret: 'whatever',
cookie: {
maxAge: 60*60*1000,
sameSite: true
}
}))
app.get('/', (req, res) => {
res.writeHead(200, {'Content-Type': 'text/html'});
var readStream = fs.createReadStream('index.html','utf8');
readStream.pipe(res);
});
app.post('/:fieldName/:flag/:time/:dashboard/:identifier/:user', (req, res) => {
console.log('POST message received', req.params);
if (req.params && req.params.fieldName) {
fs.appendFileSync(`./changeLog_${getDateTimestamp()}.csv`, `${req.params.fieldName},${req.params.flag},${req.params.time},${req.params.dashboard},${req.params.identifier},${req.params.user},${req.sessionID}\n`);
return res.send('OK')
}
res.status(400).end()
});
Client Side
function onParameterChange (parameterChangeEvent) {
parameterChangeEvent.getParameterAsync().then(function (param) {
parameterIndicator = 'Parameter'
const details = {
method: 'POST',
credentials: 'include'
//body: JSON.stringify(data),
// headers: {
// 'Content-Type': 'application/json'
// }
};
fetch(`url/${param.name}/${parameterIndicator}/${getDateTimestamp()}/${dashboardName}/${param.name}/${worksheetData}`, details).then((res) => {console.log(res);});
});
}
Here is my output showing a different session for the same user.

Answer 1

Just to illustrate my comment above, I actually have ran a quick test with a simple setup, and toggling saveUninitialized actually seems to make the difference:
// app.js
const express = require('express')
const app = express()
const session = require('express-session')
// Run the file as "node app false" or "node app true" to toggle saveUninitialized.
const saveUninitialized = process.argv[2] == "true" ? true : false
app.use(session({
resave: false,
saveUninitialized,
secret: 'whatever',
cookie: {
maxAge: 60 * 60 * 1000,
sameSite: true
}
}))
app.get("/", (req, res) => {
res.status(200).send(req.sessionID)
})
app.listen(3000, () => {
console.log('server started on http://localhost:3000')
})
// Response body
node app false
// 1st request: OTnFJD-r1MdiEc_8KNwzNES84Z0z1kp2
// 2nd request: 5UVVGng_G72Vmb5qvTdglCn9o9A4N-F6
// 3rd request: 9aGsAwnHh1p1sgINa1fMBXl-oRKcaQjM
node app true
// 1st request: StUrtHOKBFLSvl5qoFai6OQCm7TY87U-
// 2nd request: StUrtHOKBFLSvl5qoFai6OQCm7TY87U-
// 3rd request: StUrtHOKBFLSvl5qoFai6OQCm7TY87U-
But maybe there is more to it than that with your setup.