Firebase function to fetch data from Firebase DB to make Push notification

Question

I have chat app with firebase database and Firebase cloud messaging. I can send firebase notification via console but in real scenario it should be automatic. To make automatic notification,My friend wrote Index.js (Added in cloud functions) file for me but its not sending notifications.

As per our logic function should trigger whenever there is any new entries (in any node or in any room) and fetch these values by firebase function and make post request to FCM server to make notification to receiver device (get value of receiver device from token_To).

1. Message
2. Message_From
3. Time
4. Type
5. token_To

Index.js

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


var serviceAccount = require('./demofcm-78aad-firebase-adminsdk-4v1ot-2764e7b580.json');
admin.initializeApp({
  credential: admin.credential.cert(serviceAccount),
  databaseURL: "https://demofcm-78aad.firebaseio.com/"
})

// // Create and Deploy Your First Cloud Functions
// // https://firebase.google.com/docs/functions/write-firebase-functions
//
// exports.helloWorld = functions.https.onRequest((request, response) => {
//  response.send("Hello from Firebase!");
// });
exports.setUserNode = functions.auth.user().onCreate(event => {
  // ...
});

exports.notifyMsg = functions.database.ref('/{chatroom}/{mid}/')
    .onWrite(event => {

       if (!event.data.val()) {
         return console.log('Message Deleted');
       }

       const getDeviceTokensPromise = admin.database().ref('/{chatroom}/{mid}/token_to').once('value');


       return Promise.all([getDeviceTokensPromise]).then(results => {
         const tokensSnapshot = results[0];

         if (!tokensSnapshot.hasChildren()) {
           return console.log('There are no notification tokens to send to.');
         }

         const payload = {
           notification: {
             title: 'You have a new Message!',
             body: event.data.val().Message
           }
         };

         const tokens = Object.keys(tokensSnapshot.val());

         return admin.messaging().sendToDevice(tokens, payload).then(response => {

           const tokensToRemove = [];
           response.results.forEach((result, index) => {
             const error = result.error;
             if (error) {
               console.error('Failure sending notification to', tokens[index], error);

               if (error.code === 'messaging/invalid-registration-token' ||
                   error.code === 'messaging/registration-token-not-registered') {
                 tokensToRemove.push(tokensSnapshot.ref.child(tokens[index]).remove());
               }
             }
           });
           return Promise.all(tokensToRemove);
         });
       });
});

Firebase function Log

How can i fetch above mentioned values of any newly added node in same room(9810012321-9810012347) or any other room(9810012321-9810012325) from database and send it to FCM to make notification

Thanks in Advance.

Answer 1

What i did is created a Message node and I believe doing this by users key. ie, having the receiver(toId) and sender (fromId) key to send the notification. Hope it helps.

exports.sendMessageNotification = functions.database.ref('/messages/{pushId}')
.onWrite(event => {
    let message = event.data.current.val();
    console.log('Fetched message', event.data.current.val());
    let senderUid = message.fromId;
    let receiverUid = message.toId;
    let promises = [];

    console.log('message fromId', receiverUid);
    console.log('catch me', admin.database().ref(`/users/${receiverUid}`).once('value'));

    if (senderUid == receiverUid) {
        //if sender is receiver, don't send notification
        //promises.push(event.data.current.ref.remove());
        return Promise.all(promises);
    }

    let messageStats = message.messageStatus;
    console.log('message Status', messageStats);

    if (messageStats == "read") {
        return Promise.all(promises);
    }

    let getInstanceIdPromise = admin.database().ref(`/users/${receiverUid}/pushToken`).once('value');
    let getSenderUidPromise = admin.auth().getUser(senderUid);

    return Promise.all([getInstanceIdPromise, getSenderUidPromise]).then(results => {
        let instanceId = results[0].val();
        let sender = results[1];
        console.log('notifying ' + receiverUid + ' about ' + message.text + ' from ' + senderUid);
        console.log('Sender ', sender);
        var badgeCount = 1;
        let payload = {
            notification: {
                uid: sender.uid,
                title: 'New message from' + ' ' + sender.displayName,
                body: message.text,
                sound: 'default',
                badge: badgeCount.toString()
            },
            'data': { 
                'notificationType': "messaging", 
                'uid': sender.uid
          }
        };
        badgeCount++;
        admin.messaging().sendToDevice(instanceId, payload)
            .then(function (response) {
                console.log("Successfully sent message:", response);
            })
            .catch(function (error) {
                console.log("Error sending message:", error);
            });
    });
});