How to fetch firebase database data in cloud function?

Question

I am using firebase database to store my iOS app data.

I am saving user tracking data in this app which is working fine.

I have to send a push notification to the user (userID = 57411405) using push token which I am saving in 'IOS' field.

This cloud function I am using :

This cloud function is working fine. I am able to track event which save new tracking data. Here is log of this cloud function:

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

// Create and Deploy Your First Cloud Functions
// https://firebase.google.com/docs/functions/write-firebase-functions

exports.databasechanges = functions.database.ref('/users/{id}/LocationTracking').onWrite(event =>{

var eventSnapshot = event.data

console.log('UserId - ', event.params.id);

const userID = event.params.id
const root = event.data.ref.root

admin.database().ref('users/{id}/NotificationToken').on('value').then((snapshot) => {

  var token = snapshot.val().IOS;

  console.log('token',token)

  return snapshot.val();
}).catch(error => {
  console.error(error);
  res.error(500);
});

return eventSnapshot.val()

});

But on cloud function console I am getting this error:

Now, I am not able to figure out how to access this push token (IOS) and send push notification using cloud function.

Please don't show images of code. It's far better to copy the code into the question into a code block so it's easier to read and search. — Doug Stevenson
– Doug Stevenson, Commented Mar 12, 2018 at 6:57

Peter Haddad · Accepted Answer · 2018-03-13 09:30:20Z

4

To get the field "IOS", try this:

//inside the trigger function
admin.database().ref('/users/'+event.params.id+'/NotificationToken/IOS').once('v‌alue').then((snapshot) => { 
var token=snapshot.val().IOS;

 });

edited Mar 13, 2018 at 9:30

answered Mar 12, 2018 at 6:43

Peter Haddad

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5 Comments

ajeet sharma Over a year ago

I am getting this error: 24:1 error Expected catch() or return promise/catch-or-return

Peter Haddad Over a year ago

check this: stackoverflow.com/questions/48582278/…

ajeet sharma Over a year ago

Cloud function has deployed successfully but I am getting error in cloud function console. I edited my question please have a look.

Peter Haddad Over a year ago

@ajeetsharma use once() instead of on() and get the value once

ajeet sharma Over a year ago

it's not working :( . getting this error in console: TypeError: Cannot read property 'IOS' of null at admin.database.ref.once.then (/user_code/index.js:34:29) at process._tickDomainCallback (internal/process/next_tick.js:135:7)

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