So this question is pretty straightforward. I have a Cloud Function that should validate if it is a new user that is logging in with SSO (Facebook, Twitter or Google) in my web app.

Now the control is nessecary because if the user bypasses the “sign-up.html” and goes straight to “sign-in.html” and logged in, Firebase do create a uID and an Authentication is registered on all of them BUT:

No document is created in my Users collection Firestore and the “checkNewUser” Function here below never triggers.

Can you spot something missing with the code? Thanks:

const functions = require('firebase-functions');
const admin = require('firebase-admin');

admin.initializeApp();

const db = admin.firestore();

exports.checkNewUser = functions.auth.user().onCreate(async (user) => {
  const uid = user.uid;
  const email = user.email || null;
  const displayName = user.displayName || 'Anonymous';

  const userDoc = db.collection('users').doc(uid);

  const userSnapshot = await userDoc.get();

  if (!userSnapshot.exists) {
    // New user
    await userDoc.set({
      uid: uid,
      email: email,
      displayName: displayName,
      isOnline: true,
    });
  } else {
    // Existing user
    await userDoc.update({
      isOnline: true,
    });
  }

  return null;
});