How to send device to device messages using Firebase Cloud Messaging?

Question

After searching the docs I could not find any info on how to send device to device messages using FCM without the use of an external server.

For example, if I was cr

Answer 1

Google Cloud Functions make it now possible send push notifications from device-to-device without an app server. I have made cloud function which is trigger when new message is added in database

It is node.js code

'use strict';

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

exports.sendNotification = functions.database.ref('/conversations/{chatLocation}/{messageLocation}')
  .onCreate((snapshot, context) => {
      // Grab the current value of what was written to the Realtime Database.
      const original = snapshot.val();

       const toIDUser = original.toID;
       const isGroupChat = original.isGroupChat;

       if (isGroupChat) {
       const tokenss =  admin.database().ref(`/users/${toIDUser}/tokens`).once('value').then(function(snapshot) {

// Handle Promise
       const tokenOfGroup = snapshot.val()

      // get tokens from the database  at particular location get values 
       const valuess = Object.keys(tokenOfGroup).map(k => tokenOfGroup[k]);

     //console.log(' ____________ffffd((999999ffffd_________________ ' +  valuess );
    const payload = {
       notification: {
                 title:   original.senderName + " :- ",
                 body:    original.content
    }
  };

  return admin.messaging().sendToDevice(valuess, payload);



}, function(error) {

  console.error(error);
});

       return ;
          } else {
          // get token from the database  at particular location
                const tokenss =  admin.database().ref(`/users/${toIDUser}/credentials`).once('value').then(function(snapshot) {
                // Handle Promise
  // The Promise was "fulfilled" (it succeeded).

     const credentials = snapshot.val()



    // console.log('snapshot ......snapshot.val().name****^^^^^^^^^^^^kensPromise****** :- ', credentials.name);
     //console.log('snapshot.....****snapshot.val().token****^^^^^^^^^^^^kensPromise****** :- ', credentials.token);


     const deviceToken = credentials.token;

    const payload = {
       notification: {
                 title:   original.senderName + " :- ",
                 body:    original.content
    }
  };

  return admin.messaging().sendToDevice(deviceToken, payload);


}, function(error) {

  console.error(error);
});


          }





  return ;


    });