Firebase functions logs error working with Cloud Firestore and Node JS

Question

The Firebase functions by Nodejs is not retrieving the results from the data stored in the Cloud Firestore Database. Giving a:

TypeError of Undefined user_id

NodeJS Code

'use-strict'

const admin = require('firebase-admin');
const functions = require('firebase-functions');
const serviceAccount = require("./serviceAccountKey.json");

admin.initializeApp(functions.config().firebase);

exports.sendNotification = functions.firestore.document("Users/{user_id}/Notifications/{notification_id}").onWrite(event => {

const user_id = event.params.user_id;
const notification_id = event.params.notification_id;

console.console.log("User ID: " + user_id + " | Notification ID: " + notification_id);
});

Error in Logs of Firebase Functions

TypeError: Cannot read property 'user_id' of undefined at 
exports.sendNotification.functions.firestore.document.onWrite.event 
(/user_code/index.js:10:33) at Object.<anonymous> 
(/user_code/node_modules/firebase-functions/lib/cloud-functions.js:112:27) 
at next (native) at /user_code/node_modules/firebase-functions/lib/cloud- 
functions.js:28:71 at __awaiter (/user_code/node_modules/firebase- 
functions/lib/cloud-functions.js:24:12) at cloudFunction 
(/user_code/node_modules/firebase-functions/lib/cloud-functions.js:82:36) at 
/var/tmp/worker/worker.js:700:26 at process._tickDomainCallback 
(internal/process/next_tick.js:135:7)

Database Rules

service cloud.firestore {
match /databases/{database}/documents {
match /{document=**} {
allow read, write: if true; } } }

Answer 1

It looks like you're using version 1.0 of the firebase-functions module in your Cloud Functions code. The API has changed in 1.0. Please consult the migration guide to understand what changed in 1.0.

There is no longer a params property on the first argument passed to the the callback for an onWrite trigger. It was split into two arguments , a Change, and an EventContext object. The EventContext argument has a params property you should use now.