Cloud Functions for Firebase child_added

Question

I'm trying out Cloud Functions for Firebase, creating a function which will add a nickname when a new user is added to the database (not on auth). From the Firebase Documention I've found that I need to use:

ref.on("child_added", function(snapshot, prevChildKey) { //Something })

, but I cannot even get the function to deploy. My code is:

const functions = require('firebase-functions'); const admin = require('firebase-admin'); admin.initializeApp(functions.config().firebase); var ref = admin.database().ref("/users"); ref.on("child_added", function(snapshot, prevChildKey) { console.log(snapshot) })

Can someone help me?

Update:

After working on it this is now my code:

const functions = require('firebase-functions'); // Import Admin SDK var admin = require("firebase-admin"); admin.initializeApp(functions.config().firebase); var db = admin.database(); var ref = db.ref('users'); var childs = []; var nicknames = []; exports.newUser = functions.database.ref('users').onWrite(event => { const data = event.data.val(); ref.on("child_added", function(snapshot, childKey) { if (!childs.includes(childKey)) { childs.push(childKey); }; for (i in childs) { if (childs[i] == null) { childs.splice(i, 1); }; }; }); ref.once("value", function(snapshot) { for (i in childs) { var child = data[childs[i]]; if (!child.hasOwnProperty("nickname")) { console.log("Child does not have nickname: " + childs[i]); ref.child(childs[i]).update({ nickname: "user"+childs[i] }); }; }; }); });

Based on what Doug Stevenson has replied, I still need to figure out how to only do this if there's actually a new child being added (new user)

Unfortunately not. The only solution I have found is the one I posted beneath, but it still fires every time something is written to the users only when a child is added straight beneath 'users' — GKH
– GKH, Commented May 11, 2017 at 8:38

GKH · Accepted Answer · 2017-03-29 02:09:57Z

1

I figured it out. Here's the code I used:

const functions = require('firebase-functions'); var admin = require("firebase-admin"); admin.initializeApp(functions.config().firebase); var childs = []; var nicknames = []; exports.newUser = functions.database.ref('users').onWrite(event => { ref.on("child_added", function(snapshot, childKey) { if (!childs.includes(childKey)) { childs.push(childKey); } }); });

I would like it only to be called when a child is added and not every time something is written to the database (to limit usage)

edited Mar 29, 2017 at 2:09

answered Mar 29, 2017 at 1:59

GKH

1792 silver badges13 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Doug Stevenson Over a year ago

I don't think that's going to work out the way you want. You're definitely going to have problems in the future if you try to register a persistent listener inside a function like that. If you want to know when a new node is added, you have to check the previous value of the snapshot in the event to see if it's null. That's how you know a write added new data instead of modifying existing data.

GKH Over a year ago

Would it be enough with: if (snapshot.previous.val()) { return; } as suggest on codelab

Murat Yasar Over a year ago

Yes @GlennHerping, as the comment on the source code explains, // Only send a notification when a new message has been created. It should work.

Collectives™ on Stack Overflow

Cloud Functions for Firebase child_added

Update:

1 Answer 1

3 Comments

Hot Network Questions

Collectives™ on Stack Overflow

Update:

1 Answer 1

3 Comments

Related