How to retrieve metadata from Stripe session object NodeJS - node.js

Question

I am trying to pass a UID and purchase ID with Stripe Checkout session object (using metadata). Generating the session ID on my server attaching the metadata works very fine. Stripe also POSTs everything correctly to my webhook server. The problems occurs while retrieving the metadata from the session object POSTed by Stripe.
Here is the error I get
TypeError: Cannot read property 'metadata' of undefined at /app/app.js:35:32
Here is the session obj posted by Stripe-
{
"id": "evt_1GRC7lAfcfWZXl7jQ3VzNo4y",
"object": "event",
"api_version": "2019-10-17",
"created": 1585292221,
"data": {
"object": {
"id": "cs_test_gLsHqtF8XhB3C3DlWKcLtNdTitp0St8ju5qgJgl6tHrMxxWvju9gb9Li",
"object": "checkout.session",
"billing_address_collection": null,
"cancel_url": "https://andropaym.firebaseapp.com/fail.html",
"client_reference_id": null,
"customer": "cus_GzASi1Klpydh8x",
"customer_email": null,
"display_items": [
{
"amount": 37500,
"currency": "inr",
"custom": {
"description": "Carefully modified Linux Distro Bundle for Android.",
"images": null,
"name": "Modded OS Bundle"
},
"quantity": 1,
"type": "custom"
}
],
"livemode": false,
"locale": null,
"metadata": {
"uid": "EB1m6nAOTVNcQhHO2O7COspap8y1",
"payID": "GPA.5620-9852-7063-44324"
},
"mode": "payment",
"payment_intent": "pi_1GRC7EAfcfWZXl7jhixrWHRS",
"payment_method_types": [
"card"
],
"setup_intent": null,
"shipping": null,
"shipping_address_collection": null,
"submit_type": null,
"subscription": null,
"success_url": "https://andropaym.firebaseapp.com/success.html"
}
},
"livemode": false,
"pending_webhooks": 4,
"request": {
"id": null,
"idempotency_key": null
},
"type": "checkout.session.completed"
}
Here is my webhook code -
const express = require('express');
const app = express();
const bodyParser = require('body-parser');
const stripe = require('stripe')('sk_test_xxxx');
const endpointSecret = 'whsec_xxxx';
// set the port of our application
// process.env.PORT lets the port be set by Heroku
var port = process.env.PORT || 8080;
app.post('/', bodyParser.raw({type: 'application/json'}), (request, response) => {
const sig = request.headers['stripe-signature'];
let event;
try {
event = stripe.webhooks.constructEvent(request.body, sig, endpointSecret);
} catch (err) {
return response.status(400).send(`Webhook Error: ${err.message}`);
}
function handleCheckoutSession(uid) {
// Here we are getting the session obj and we can process it to check for the things we need
console.log("UID is " + uid);
}
// Handle the checkout.session.completed event
if (event.type === 'checkout.session.completed') {
const session = event.data.object;
let uid = request.data.metadata.uid;
// Fulfill the purchase...
handleCheckoutSession(uid);
}
// Return a response to acknowledge receipt of the event
response.json({received: true});
});
app.listen(port, function () {
console.log('Our app is running on http://localhost:' + port);
});
module.exports = app;
The code works fine without the metadata being parsed
More code links:
1. Highlighted error webhook code - https://gist.github.com/imprakharshukla/1e2315615983e0e9d492d2288e159832#file-webhook_backend-js-L40

Answer 1

You need to use the object returned by stripe.constructEvent, not the request body.
Change
let uid = request.data.metadata.uid;
to
let uid = session.metadata.uid
and it should work as expected.