How to implement Stripe payment in Firestore without using firebase.auth

Question

I'm trying to use Stripe payments in my node.js app to sell products to users on whatsapp.

I installed the stripe extension: stripe/firestore-stripe-payments@0.3.3 and followed the instructions in the documentation:

const docRef = await db
  .collection('customers')
  .doc(currentUser.uid)
  .collection('checkout_sessions')
  .add({
    price: 'price_1GqIC8HYgolSxxxxxxxxx',
    success_url: window.location.origin,
    cancel_url: window.location.origin,
  });
// Wait for the extension to attach CheckoutSession
docRef.onSnapshot((snap) => {
  const { error, url } = snap.data();
  if (error) {
    // Show the error to the client and check the cloud function logs in the Firebase console.
    alert(`An error occurred: ${error.message}`);
  }
  if (url) {
    // We have a Stripe Checkout URL, let's redirect.
    window.location.assign(url);
  }
});

I receive the following error in the cloud console:

❗️[Error]: Failed to create a Checkout session for document [maxxxxxxxxxA]: The provided identifier does not have a corresponding user record.

I found that I need to use the userId from Firebase Authentication, but since I'm running my service in a function (backend server), there is no client/user in the auth.

Is there another way to create (individual) stripe checkout links? Is there a way to use Firebase Authentication without a client?

Thanks in advance.

I tried using auth,

import { getAuth } from "firebase/auth";

const auth = getAuth();
const user = auth.currentUser;

But I get the following error: FirebaseError: Firebase: Options need to be provided when not deploying to hosting via source. (app/no-options)

I tried this: https://stackoverflow.com/a/74732162/21612440

and gotTypeError: Cannot read property 'getProvider' of undefined (read 'getProvider')

Answer 1

Cloud functions (in principle) run without the context of the currently authenticated user. Therefore, in cloud functions, auth.currentUser is almost meaningless since each request may come from a different user.

However, you can pass any UID you want to the Firestore database here .doc(currentUser.uid). So if you can determine the relevant UID in some other (safe) way, you can pass that value and the Stripe extension will handle it for that user.