We Keep Coding

Firebase Cloud Function error: Registration token(s) provided to sendToDevice() must be a non-empty string or a non-empty array

I want to send a notification to all users who are confirmed guests when the object confirmedGuests is created in the Firebase Realtime Database.
So, I first create an array of all the users from confirmedGuests object. Then, I iterate through all these users and push their deviceTokens to an array of deviceTokens. The array allDeviceTokens is expected to be the array of device tokens of all users in confirmedGuests.
However, when confirmedGuests object is created, the function returns an error.
Below is my cloud function
exports.sendNotification = functions.database
.ref('/feed/{pushId}/confirmedGuests')
.onCreate((snapshot, context) => {
const pushId = context.params.pushId;
if (!pushId) {
return console.log('missing mandatory params for sending push.')
}
let allDeviceTokens = []
let guestIds = []
const payload = {
notification: {
title: 'Your request has been confirmed!',
body: `Tap to open`
},
data: {
taskId: pushId,
notifType: 'OPEN_DETAILS', // To tell the app what kind of notification this is.
}
};
let confGuestsData = snapshot.val();
let confGuestItems = Object.keys(confGuestsData).map(function(key) {
return confGuestsData[key];
});
confGuestItems.map(guest => {
guestIds.push(guest.id)
})
for(let i=0; i<guestIds.length; i++){
let userId = guestIds[i]
admin.database().ref(`/users/${userId}/deviceTokens`).once('value', (tokenSnapshot) => {
let userData = tokenSnapshot.val();
let userItem = Object.keys(userData).map(function(key) {
return userData[key];
});
userItem.map(item => allDeviceTokens.push(item))
})
}
return admin.messaging().sendToDevice(allDeviceTokens, payload);
});

You're loading each user's device tokens from the realtime database with:
admin.database().ref(`/users/${userId}/deviceTokens`).once('value', (tokenSnapshot) => {
This load operation happens asynchronously. This means that by the time the admin.messaging().sendToDevice(allDeviceTokens, payload) calls runs, the tokens haven't been loaded yet.
To fix this you'll need to wait until all tokens have loaded, before calling sendToDevice(). The common approach for this is to use Promise.all()
let promises = [];
for(let i=0; i<guestIds.length; i++){
let userId = guestIds[i]
let promise = admin.database().ref(`/users/${userId}/deviceTokens`).once('value', (tokenSnapshot) => {
let userData = tokenSnapshot.val();
let userItem = Object.keys(userData).map(function(key) {
return userData[key];
});
userItem.map(item => allDeviceTokens.push(item))
return true;
})
promises.push(promise);
}
return Promise.all(promises).then(() => {
return admin.messaging().sendToDevice(allDeviceTokens, payload);
})

Get Firebase Database Value into a Cloud Function

I'm currently using Firebase Functions to send automatic push notifications when the database is uploaded. It's working perfectly, I'm just wondering how I can get a specific value from my database, for example PostTitle and display it on, for example title.
In Firebase my database is /post/(postId)/PostTitle
const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);
// database tree
exports.sendPushNotification = functions.database.ref('/posts/{id}').onWrite(event =>{
const payload = {
notification: {
title: 'This is the title.',
body: 'There is a new post available.',
badge: '0',
sound: 'default',
}
};
return admin.database().ref('fcmToken').once('value').then(allToken => {
if (allToken.val()){
const token = Object.keys(allToken.val());
console.log(`token? ${token}`);
return admin.messaging().sendToDevice(token, payload).then(response =>{
return null;
});
}
return null;
});
});

If I understand correctly that you want to get the PostTitle from the node that triggers the Cloud Function, the following should do the trick:
const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);
// database tree
exports.sendPushNotification = functions.database.ref('/posts/{id}').onWrite(event =>{
const afterData = event.data.val();
const postTitle = afterData.PostTitle; //You get the value of PostTitle
const payload = {
notification: {
title: postTitle, //You then use this value in your payload
body: 'There is a new post available.',
badge: '0',
sound: 'default',
}
};
return admin.database().ref('fcmToken').once('value').then(allToken => {
if (allToken.val()){
const token = Object.keys(allToken.val());
console.log(`token? ${token}`);
return admin.messaging().sendToDevice(token, payload)
} else {
throw new Error('error message to adapt');
}
})
.catch(err => {
console.error('ERROR:', err);
return false;
});
});
Note the following points:
You are using the old syntax for Cloud Functions, i.e. the one of versions <= v0.9.1. You should migrate to the new version and syntax, as explained here: https://firebase.google.com/docs/functions/beta-v1-diff#realtime-database
I have re-organised your promise chaining and also added a catch() at the end of the chain.

I'd use ...
var postTitle = event.data.child("PostTitle").val;
while possibly checking, it the title even has a value
... before sending out any notifications.

Firebase TypeError: Cannot read property 'val' of undefined

I have tried Firebase cloud function for sending a notification.My project structure
and this is the index.js,
const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp();
exports.pushNotification = functions.database.ref('/messages').onWrite( event => {
console.log('Push notification event triggered');
const message = event.data.val();
const user = event.data.val();
console.log(message);
console.log(user);
const topic = "myTopic";
const payload = {
"data": {
"title": "New Message from " + user,
"detail":message,
}
};
return admin.messaging().sendToTopic(topic, payload);
});
The above code is misconfigured, when I deploy in Node.js, LOG in Function shows:
"TypeError: Cannot read property 'val' of undefined".
What Actually I am trying to do :
I am trying to extract info from snapshot load into that index.js so that when a new child gets added to Real-time database, it should trigger a notification payload with a title and body.
In Android, I use a child listener, for listening when a new record is added
FirebaseDatabase.getInstance().getReference().child("messages")
OnChildAdded(.....){
if (dataSnapshot != null) {
MessageModel messageModel = dataSnapshot.getValue(MessageModel.class);
if (messageModel != null) {
// do whatever
}
}
But in index.js, I could not able to parse that.
A bit guidance how to fixate index.js according to my database structure would be immensely appreciated.
PS- I have never done coding in JS
If you want more context, I'd be happy to provide it.

Change this:
exports.pushNotification = functions.database.ref('/messages').onWrite( event => {
const message = event.data.val();
const user = event.data.val();
});
to this:
exports.pushNotification = functions.database.ref('/messages').onWrite(( change,context) => {
const message = change.after.val();
});
Please check this:
https://firebase.google.com/docs/functions/beta-v1-diff#realtime-database
The cloud functions were changed and now onWrite has two parameters change and context
The change has two properties before and after and each of these is a DataSnapshot with the methods listed here:
https://firebase.google.com/docs/reference/admin/node/admin.database.DataSnapshot

'use strict'
const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);
exports.sendNotification = functions.database.ref('/NOTIFICATIONS/{UserId}/{{notification_id}').onWrite((change, context) =>
{
const UserId = context.params.UserId;
const notification = context.params.notification;
console.log('The user Id is : ', UserId);
if(!change.after.exists())
{
return console.log('A Notification has been deleted from the database : ', notification_id);
}
if (!change.after.exists())
{
return console.log('A notification has been deleted from the database:', notification);
return null;
}
const deviceToken = admin.database().ref(`/USER/${UserId}/device_token`).once('value');
return deviceToken.then(result =>
{
const token_id = result.val();
const payload = {
notification : {
title : "Friend Request",
body : "You've received a new Friend Request",
icon : "default"
}
};
return admin.messaging().sendToDevice(token_id, payload).then(response => {
console.log('This was the notification Feature');
});
});
});

Notification with cloud function firebase, JavaScript

I am following a tutorial to deploy a function to firebase. when I deploy I get an unknown error whereas the tutor doesn't. I have looked through this line for line and it's exact. Can anyone else shed any light on this?
// The Cloud Functions for Firebase SDK to create Cloud Functions and setup triggers.
const functions = require('firebase-functions');
// The Firebase Admin SDK to access the Firebase Realtime Database.
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);
const ref = admin.database().ref
exports.sendPushNotification = functions.database.ref('/posts/{postId}/question').onWrite(event => {
const payload = {
notification: {
title: 'A Question has been posted',
body: 'Check out the question posted ',
badge: '1',
sound: 'default',
}
};
return admin.database().ref('fcmToken').once('value').then(allToken => {
if (allToken.val()) {
const token = Object.keys(allToken.val());
return admin.messaging().sendToDevice(token, payload).then(response => {
});
};
});
});

Cloud Functions expects a returned Promise or value. Add a return for the case where there is no token value found in the database:
exports.sendPushNotification = functions.database.ref('/posts/{postId}/question').onWrite(event => {
const payload = {
notification: {
title: 'A Question has been posted',
body: 'Check out the question posted ',
badge: '1',
sound: 'default',
}
};
return admin.database().ref('fcmToken').once('value').then(allToken => {
if (allToken.val()) {
const token = Object.keys(allToken.val());
return admin.messaging().sendToDevice(token, payload).then(response => {
});
} else {
return null; // <= ADDED
}
});
});

Firebase Cloud Messaging for sending notification to all the registered devices not working

For my magazine app,I am using Firebase service.One function of this android app is whenever new article is published;notification of new article is sent to all the devices.
I am saving all the device tokens in db like this:
FCMToken
{
userid:deviceToken
}
So whenever new node is added in "published" key in firebase db,FCM function is triggered and messages is sent to all the devices:
Below is my code in javascript for FCM function:
'use strict'
const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);
exports.sendNotification = functions.database.ref('/published/{msg_id}').onWrite(event => {
const snapshot = event.data;
// Only send a notification when a new message has been created.
if (snapshot.previous.val()) {
return;
}
const msg_id = event.params.msg_id;
const msg_val=admin.database().ref(`messages/${msg_id}`).once('value');
return msg_val.then(msgResult =>{
const msg_title=msgResult.val().title;
const user_id=msgResult.val().userId;
console.log('msg title is',msg_title);
console.log('We have a new article : ', msg_id);
const payload={
data : {
title:"New Article",
body: msg_title,
msgid : msg_id,
userid : user_id
}
};
// const deviceToken = admin.database().ref('/FCMToken/{user_id}').once('value');
admin.database().ref('/FCMToken').on("value", function(dbsnapshot)
{
dbsnapshot.forEach(function(childSnapshot) {
//var childKey = childSnapshot.key;
const childData = childSnapshot.val();
const deviceToken=console.log("device token" + childSnapshot.val());
return admin.messaging().sendToDevice(childData,payload).then(response=>{
console.log("This was notification feature")
console.log("response: ", response);
})
.catch(function(error)
{
console.log("error sending message",error)
});
});
});
});
});
For some reason,notification is only sent to only 1 device(the first token in FCM node).
Update:
I have updated my code and using promise,but for some reason it is still not working,just sending notification to first device token.
'use strict'
const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);
exports.sendNotification = functions.database.ref('/published/{msg_id}').onWrite(event => {
const snapshot = event.data;
// Only send a notification when a new message has been created.
if (snapshot.previous.val()) {
return;
}
const msg_id = event.params.msg_id;
const msg_val=admin.database().ref(`messages/${msg_id}`).once('value');
return msg_val.then(msgResult =>{
const msg_title=msgResult.val().title;
const user_id=msgResult.val().userId;
console.log('msg title is',msg_title);
console.log('We have a new article : ', msg_id);
const payload={
data : {
title:"New Article",
body: msg_title,
msgid : msg_id,
userid : user_id
}
};
const promises=[];
// const deviceToken = admin.database().ref('/FCMToken/{user_id}').once('value');
admin.database().ref('/FCMToken').once('value').then(function(dbsnapshot)
{
dbsnapshot.forEach(function(childSnapshot) {
//var childKey = childSnapshot.key;
const childData = childSnapshot.val();
const deviceToken=console.log("device token" + childSnapshot.val());
const promise = admin.messaging().sendToDevice(childData,payload).then(response=>{
promises.push(promise)
console.log("This was notification feature")
console.log("response: ", response);
})
return Promise.all(promises)
.catch(function(error)
{
console.log("error sending message",error)
});
});
});
});
});
Response object is giving this output: response: { results: [ { error: [Object] } ],
canonicalRegistrationTokenCount: 0,
failureCount: 1,
successCount: 0,
multicastId: 6411440389982586000 }

You're not using promises correctly throughout your function. There are two things wrong.
First, you should be querying the database using once() instead of on(), and using the promise returned from it in order to proceed to the next item of work:
admin.database().ref('/FCMToken').on("value")
.then(result => /* continue your work here */)
Also, you can't return a promise out of the forEach loop. Instead, you need to return a promise at the top level of the function, as the very last step in the function. This promise needs to resolve when all of the work is done in this function. For your function, this means when all of the messages are sent. You'll have to collect all the promises for all of the messages in an array, then return a single promise that resolves when they all resolve. The general form of that looks like this:
const promises = []
dbsnapshot.forEach(function(childSnapshot) {
// remember each promise for each message sent
const promise = return admin.messaging().sendToDevice(...)
promises.push(promise)
})
// return a single promise that resolves when everything is done
return Promise.all(promises)
Please take care to learn how promises work in JavaScript. You won't be able to write effective functions without dealing with promises correctly.

So I figured out another method to get values.
const tokens= Object.keys(tokensSnapshot.val()).map(e => tokensSnapshot.val()[e]);
Below is my complete method:
'use strict'
const functions = require('firebase-functions');
const admin = require('firebase-admin');
//Object.values = require('object.values');
admin.initializeApp(functions.config().firebase);
exports.sendNotification = functions.database.ref('/published/{msg_id}').onWrite(event => {
const snapshot = event.data;
// Only send a notification when a new message has been created.
if (snapshot.previous.val()) {
return;
}
const msg_id = event.params.msg_id;
const msg_val=admin.database().ref(`messages/${msg_id}`).once('value');
return msg_val.then(msgResult =>{
const msg_title=msgResult.val().title;
const user_id=msgResult.val().userId;
console.log('msg title is',msg_title);
console.log('We have a new article : ', msg_id);
const payload={
data : {
title:"New Article",
body: msg_title,
msgid : msg_id,
userid : user_id
}
};
const getDeviceTokensPromise = admin.database().ref('/FCMToken').once('value');
return Promise.all([getDeviceTokensPromise, msg_title]).then(results => {
const tokensSnapshot = results[0];
const msgi = results[1];
if (!tokensSnapshot.hasChildren()) {
return console.log('There are no notification tokens to send to.');
}
console.log('There are', tokensSnapshot.numChildren(), 'tokens to send notifications to.');
console.log("tokenslist",tokensSnapshot.val());
const tokens= Object.keys(tokensSnapshot.val()).map(e => tokensSnapshot.val()[e]);
//var values = Object.keys(o).map(e => obj[e])
return admin.messaging().sendToDevice(tokens, payload).then(response => {
// For each message check if there was an error.
const tokensToRemove = [];
response.results.forEach((result, index) => {
const error = result.error;
if (error) {
console.error('Failure sending notification to', tokens[index], error);
// Cleanup the tokens who are not registered anymore.
}
});
return Promise.all(tokensToRemove);
});
});
});
});