Setting state parameter to a Stripe query to pass a FireStore uuid - firebase

Question

I am trying to pass a FirebaseFirestore User Uid to a Stripe / firestore cloud function.
So I would have an https query like following :
https://connect.stripe.com/express/oauth/authorize?response_type=code&client_id={accountid}&scope=read_write to open in a Webview
Here is my function
exports.connectStripeExpressAccount = functions.https.onRequest((req, res) =>{
console.log('query state is ----> ' + req.query.state);
const authCode = req.query.code;
return stripe.oauth.token({
grant_type: 'authorization_code',
code: authCode,
}).then(async response => {
var connected_account_id = response.stripe_user_id;
const uid = req.query.state
const writeResult = await admin.firestore().collection('Registration').doc(uid)
.set({'customer_id': connected_account_id});
return res.send("Well done, account integration is completed. You can now close the window and go back to the app");
});
});

Answer 1

For new integrations with Express Accounts you should ideally be using the Account Links functionality instead of OAuth. That said, if you provide the state value, it should carry through, so I'd make sure you're actually providing it when opening the WebView.

Answer 2

If the User uid is stored in the query parameter state and the URL looks like this:
https://connect.stripe.com/express/oauth/authorize?response_type=code&client_id=ca_JCV8JW9ZIjBaGkwkhbDDDQegceWGidqh&scope=read_write&state=useruidxxx
Your code would look like this:
exports.connectStripeExpressAccount = functions.https.onRequest((req, res) =>{
console.log('query state is ----> ' + req.query.state);
const authCode = req.query.code;
return stripe.oauth.token({
grant_type: 'authorization_code',
code: authCode,
}).then(async response => {
var connected_account_id = response.stripe_user_id;
const uid = req.query.state
const writeResult = await admin.firestore().collection('Registration').doc(uid)
.set({'customer_id': connected_account_id});
return res.send("Well done, account integration is completed. You can now close the window and go back to the app");
});
});