Device token management in Firebase - Mini Project: Build & Apply

Device Token Management with Firebase

📖 Scenario: You are building a mobile app that sends notifications to users. To do this, you need to manage device tokens securely and efficiently using Firebase Cloud Messaging (FCM).

🎯 Goal: Create a simple Firebase Cloud Function to store device tokens in Firestore, update them when needed, and delete tokens when users log out.

📋 What You'll Learn

Create a Firestore collection called deviceTokens to store tokens.

Write a Cloud Function to add a new device token to Firestore.

Write a Cloud Function to update an existing device token.

Write a Cloud Function to delete a device token when a user logs out.

💡 Why This Matters

🌍 Real World

Managing device tokens is essential for sending push notifications to users in mobile apps securely and efficiently.

💼 Career

This project teaches skills used by cloud engineers and backend developers working with Firebase to handle user device data and notifications.

1

Create Firestore collection and add device token

Create a Cloud Function called addDeviceToken that takes userId and token as parameters and adds a document to the deviceTokens collection with userId as the document ID and token as a field.

Firebase

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

// Create addDeviceToken function
// Your code here

Need a hint?

Use functions.https.onCall to create the function. Use admin.firestore().collection('deviceTokens').doc(userId).set({ token: token }) to add the token.

2

Add update token configuration

Create a variable called updateOptions with the value { merge: true } to allow updating existing tokens without overwriting the whole document.

Firebase

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

exports.addDeviceToken = functions.https.onCall(async (data, context) => {
  const userId = data.userId;
  const token = data.token;
  await admin.firestore().collection('deviceTokens').doc(userId).set({ token: token });
  return { message: 'Token added successfully' };
});

// Create updateOptions variable
// Your code here

Need a hint?

Define const updateOptions = { merge: true } to use later for updating tokens.

3

Create updateDeviceToken function

Create a Cloud Function called updateDeviceToken that takes userId and newToken as parameters and updates the token field in the deviceTokens collection using updateOptions to merge changes.

Firebase

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

const updateOptions = { merge: true };

exports.addDeviceToken = functions.https.onCall(async (data, context) => {
  const userId = data.userId;
  const token = data.token;
  await admin.firestore().collection('deviceTokens').doc(userId).set({ token: token });
  return { message: 'Token added successfully' };
});

// Create updateDeviceToken function
// Your code here

Need a hint?

Use set with updateOptions to update the token without overwriting the whole document.

4

Create deleteDeviceToken function

Create a Cloud Function called deleteDeviceToken that takes userId as a parameter and deletes the corresponding document from the deviceTokens collection.

Firebase

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

const updateOptions = { merge: true };

exports.addDeviceToken = functions.https.onCall(async (data, context) => {
  const userId = data.userId;
  const token = data.token;
  await admin.firestore().collection('deviceTokens').doc(userId).set({ token: token });
  return { message: 'Token added successfully' };
});

exports.updateDeviceToken = functions.https.onCall(async (data, context) => {
  const userId = data.userId;
  const newToken = data.newToken;
  await admin.firestore().collection('deviceTokens').doc(userId).set({ token: newToken }, updateOptions);
  return { message: 'Token updated successfully' };
});

// Create deleteDeviceToken function
// Your code here

Need a hint?

Use delete() on the document reference to remove the token.