Firebase Functions cannot always save a user to Realtime Database

Question

I use Firebase auth and realtime database in my Android app. This is the code that I use in Firebase functions to save the user email into the realtime database when they register in the app with email:

'use strict';

const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);

exports.initializeUserProfile = functions.auth.user().onCreate(user => {
    const userUid = user.uid;

    return admin.auth().getUser(userUid).then(userRecord => {
        const userProfile = {
            email: userRecord.email
        };
        return admin.database().ref(`/profiles/${userUid}`).set(userProfile);
    }).catch(error => {
        console.log("Error fetching user data: ", error);
    });
});

exports.removeUserProfile = functions.auth.user().onCreate(user => {
    const userUid = user.uid;

    return admin.database().ref(`/profiles/${userUid}`).remove();
});

When I register an user in the android app (I use the built in registration UI for Firebase), it gives me no error in the Functions logs:

My problem is that although I don't have an error in the log and the user was added to the Firebase Authentication section, the Realtime database doesn't contain the node with the email. The problem is very sporadic. Sometimes it registers it fine into the realtime database, but sometimes it doesn't (like in the log of Jun 25). In the Android app I try to query the database node of the user after registration to display they email and there I get an error (maybe it is an bug in my app, but anyhow, that code up there should be run on server side and the email should be in the Firebase Realtime Database).

What I also don't know is that why do I have those removeUserProfile calls in the log as I didn't remove any user from the Authentication database or from the Realtime database.

Renaud Tarnec Renaud Tarnec · Accepted Answer · 2018-06-26T08:19:44

Actually, your two Cloud Functions are triggered with exactly the same event, i.e. onCreate(user). So it is normal that they are triggered (almost) simultaneously and that you see the two invocations in the log.

Since you write that "The problem is very sporadic" what is probably happening is that the new record is first created at /profiles/${userUid} by the initializeUserProfile Cloud Function BUT is then removed by the removeUserProfile Cloud Function.

So you should change the trigger of the removeUserProfile Cloud Function to onDelete():

exports.removeUserProfile = functions.auth.user().onDelete((user) => {
   const userUid = user.uid;

   return admin.database().ref(`/profiles/${userUid}`).remove();.
});

Firebase Functions cannot always save a user to Realtime Database

1 Answers