Send Firebase Cloud Messaging notifications for new followers.

This sample demonstrates how to send a Firebase Cloud Messaging (FCM) notification from a Realtime Database triggered Function. The sample also features a Web UI to experience the FCM notification.

Functions Code

See file functions/index.js for the code.

Sending the notification is performed using the request-promise-native package to send a REST request to the FCM API. The Web client writes the individual device tokens to the realtime database which the Function uses to send the notification.

The dependencies are listed in functions/package.json.

Sample Database Structure

Users sign into the app and are requested to enable notifications on their browsers. If they successfully enable notifications the device token is saved into the datastore under /users/$uid/notificationTokens.:

/functions-project-12345
    /users
        /Uid-12345
            displayName: "Bob Dole"
            /notificationTokens
                1234567890: true
            photoURL: "https://lh3.googleusercontent.com/..."

If a user starts following another user we'll write to /followers/$followedUid/$followerUid:

/functions-project-12345
    /followers
        /followedUid-12345
            followerUid-67890: true
    /users
        /Uid-12345
            displayName: "Bob Dole"
            /notificationTokens
                1234567890: true
            photoURL: "https://lh3.googleusercontent.com/..."

Trigger rules

The function triggers every time the value of a follow flag changes at /followers/$followedUid/$followerUid.

Deploy and test

This sample comes with a web-based UI for testing the function. To test it out:

• Create a Firebase Project using the Firebase Developer Console
• Enable billing since Functions require billing.
• Enable Google Provider in the Auth section
• Import and configure Firebase in the index.html where the TODO is located
• Deploy your project using firebase deploy
• Open the app and start following a user, this will send a notification to him.