Cloud Function in Firebase Realtime Database

Question

I aim to have a databse trigger such that when there is a change in the "Players" databse node, there will be a corresponding set () function at a different firebase node called users.

Below is the cloud function I have been working on:

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);

exports.update = functions.database.ref('/Player')
    .onWrite(event=>{
      console.log(event.data);
      var ref = admin.database().ref(`/users/{user.uid}/week1`);
      ref.set(10);
      return;

    });

The issue is that the cloud function returns the error:

Error: Firebase.child failed: First argument was an invalid path: "/users/{user.uid}/week1". Paths must be non-empty strings...

There are multiple users as follows so is there a way I can access what the user uid will be for each user and refer to this within me cloud function?:

 users: {
   user uid (generated by push) : {
       deviceToken : "tokenID",
       name : "Display Name"
   },
   anotherUserID : {
       deviceToken : "tokenID",
       name : "Display Name"
   }

The Players node is as follows :

{
"players" : [
       {"name" : "Yasin 'YB' Amusan", 
        "Team" : "Industry",
        "price": 8000000, 
        "position": "forward", 
        "image":"http://res.cloudinary.com/deji/image/upload/v1489787662/blank_photo_mqvivv.png", 
        "goals": 0, 
        "assists" : 0, 
        "Y" : 0, 
        "R" : 0},
       {"name" : "Hassan 'Hasi' Akinyera",
        "Team" : "Industry", 
        "price": 5000000, 
        "position": "defender",
        "image":"http://res.cloudinary.com/deji/image/upload/v1489787662/blank_photo_mqvivv.png",
        "goals": 0, 
        "assists" : 0,
        "Y" : 0,
        "R" : 0},
       {"name" : "Femi 'Fabio' Awoniyi",
        "Team" : "Industry",
        "price": 9000000,
        "position": "defender",
        "image":"http://res.cloudinary.com/deji/image/upload/v1489787662/blank_photo_mqvivv.png",
        "goals": 0, 
        "assists" : 0, 
        "Y" : 0, 
        "R" : 0},
       {"name" : "Deji 'Dej' Awoniyi",
        "Team" : "Industry",
        "price": 7000000,
        "position": "forward",
        "image":"http://res.cloudinary.com/deji/image/upload/v1489787662/blank_photo_mqvivv.png",
        "goals": 0, 
        "assists" : 0, 
        "Y" : 0, 
        "R" : 0},
       {"name" : "Koye 'K10' Kekere-Ekun",
        "Team" : "Industry",
        "price": 9000000,
        "position":"midfielder",
        "image":"http://res.cloudinary.com/deji/image/upload/v1489787662/blank_photo_mqvivv.png",
        "goals": 0, 
        "assists" : 0, 
        "Y" : 0, 
        "R" : 0},
       {"name" : "Teni 'Teezee' Zacchaeus",
        "Team" : "Industry",
        "price": 6000000, 
        "position":"hybrid",
        "image":"http://res.cloudinary.com/deji/image/upload/v1489787662/blank_photo_mqvivv.png",
        "goals": 0, 
        "assists" : 0, 
        "Y" : 0, 
        "R" : 0},
       {"name" : "Bolaji 'Boj' Odojukan",
        "Team" : "Industry",
        "price": 7000000,
        "position":"forward",
        "image":"http://res.cloudinary.com/deji/image/upload/v1489787662/blank_photo_mqvivv.png",
        "goals": 0, 
        "assists" : 0, 
        "Y" : 0, 
        "R" : 0},
       {"name" : "Ernest",
        "Team" : "Industry",
        "price": 6000000,
        "position":"defender"
}

Right now you're trigger on /Player, so there is no concept on a user.uid. What does the Player node look like? — Frank van Puffelen
@FrankvanPuffelen hey. I've edited the question to show the Player node. Regarding your comment I now see that there is no concept of a user.uid in the Player node so how will i access the database reference I aim to access re: admin.database().ref(/users/{user.uid}/week1); — Kola Ayanwale
I'm having a hard time understanding your use-case and thus providing help. Maybe somebody else understands it well enough to help. — Frank van Puffelen

Tristan Tristan · Accepted Answer · 2018-03-13T23:57:03

There are a couple issues with your function, I will not rewrite the function for you, but will point out some things.

First, I suggest taking a look at these docs: https://firebase.google.com/docs/functions/get-started

Your trigger reference is not correct. Your database node is "players" not "Player"
Your var ref is not correct either. Are you trying to insert the user id from a variable that is not in your code? You will need to know the user's id before you can set values.

Edit: I suggest adding the user uid to the players ? Then on function execution you can access the user uid by doing something similar to this:

var player = event.data.val();
var uid = player['useruid'];

It is a little hard to tell what you are after.

Cloud Function in Firebase Realtime Database

1 Answers