Cloud Functions for Firebase: Not sending notification to all users - node.js

Question

I have created an e-commerce Android app with Firebase and a Flutter app to update the Firebase nodes.
I want to send a notification to all users whenever the admin updates the exchange rate.
Below is the code I wrote to send the update notification to all registered tokens using a Cloud Function but it only sends the notification to the Flutter app instead of both apps.
I don't know what I am doing wrong.
Here is my functions code:
const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);
exports.helloWorld=functions.database.ref('Rates').onUpdate(evt =>{
const payload={
notification:{
title:"Today's Rate",
body :"Click here to see today's gold rate",
badge: '1',
sound: 'default'
}
}
return admin.database().ref('fcm-token').once('value').then(allToken =>{
if(allToken.val()){
console.log('token available');
const token = Object.keys(allToken.val());
console.log(admin.messaging().sendToDevice(token, payload));
return admin.messaging().sendToDevice(token, payload);
}else{
console.log('No Token Available');
throw new Error("Profile doesn't exist")
}
});
});
This is an image of my Realtime Database Structure.

Answer 1

Based on your provided screenshot of your database, the data below /fcm-token in your database has two different formats.
When you added the data manually, you used the format:
{
"fcm-token": {
"someRegistrationToken": {
"token": "someRegistrationToken"
},
"someOtherRegistrationToken": {
"token": "someOtherRegistrationToken"
}
...
},
...
}
Whereas, from your "auto registered" entries, you added the tokens using:
{
"fcm-token": {
"somePushId": {
"fcmToken": "someRegistrationToken"
},
"someOtherPushId": {
"fcmToken": "someOtherRegistrationToken"
},
...
},
...
}
In your Cloud Functions code, you collect all the keys stored under /fcm-token into an array using Object.keys(allToken.val()) which will give you an array containing a mix of push IDs and FCM tokens which is not what you want and is why some devices are missing notifications.
So in short, decide on one format or the other.
Temporary work-around
With your existing mixed structure, you can use the following that will ignore what you use as the key and only extracts the token:
return admin.database().ref('fcm-token').once('value').then(allTokensSnapshot => {
if (allTokensSnapshot.exists()) {
console.log('Tokens available');
const tokenArray = [];
allTokensSnapshot.forEach((tokenSnapshot) => {
let token = tokenSnapshot.hasChild('fcmToken')
? tokenSnapshot.child('fcmToken').val()
: tokenSnapshot.child('token').val();
tokenArray.push(token);
});
return admin.messaging().sendToDevice(tokenArray, payload);
} else {
console.log('No tokens available');
throw new Error('No tokens available');
}
});
Database flattening
Personally, I'd flatten it out so you can use your code as-is, but this would require changing the way you add tokens to the database:
Database structure:
{
"fcm-token": {
"someRegistrationToken": true,
"someOtherRegistrationToken": true,
...
}
}
(You could also use the device owner's user ID instead of true if desired)
Client code:
FirebaseInstanceId.getInstance().getInstanceId()
.addOnSuccessListener(new OnSuccessListener<InstanceIdResult>() {
#Override
public void onSuccess(InstanceIdResult result) {
DatabaseReference allTokensRef = FirebaseDatabase.getInstance().getReference().child("fcm-token");
String token = result.getToken();
Log.e("Test", "FCM Registration Token: " + token);
SharedPreferences preferences = this.getSharedPreferences("com.jk.jkjwellers", MODE_PRIVATE);
if(!(preferences.getBoolean("FCMAdded", false))){
allTokensRef.child(token).setValue(true);
preferences.edit().putBoolean("FCMAdded",true).apply();
}
}
})
.addOnFailureListener(new OnFailureListener() {
#Override
public void onFailure(#NonNull Exception e) {
Log.e("Test", "Failed to get FCM registration token", e);
}
});

Answer 2

Not sure, but try replacing
databaseReference.push().setValue(new Tokens(token));
with
databaseReference.child(token).setValue(new Tokens(token));