Sending an email automatically in Firebase

If you want to generate an automatic email when a branch in your Realtime Database changes, it can be done using Firebase Cloud Functions.

First of all, install nodemailer:

shell
npm install nodemailer

nodemailer makes it easy as cake to send mails via Node.js. 🍰

Then, you will need to install Firebase CLI and init a project selecting Firebase Cloud Functions:

shell
firebase init

Then, open the file functions/index.js:

jsx
const functions = require('firebase-functions');

// // Create and Deploy Your First Cloud Functions
// // https://firebase.google.com/docs/functions/write-firebase-functions
//
// exports.helloWorld = functions.https.onRequest((request, response) => {
//  response.send("Hello from Firebase!");
// });

Delete the commented out code. To create a new function, you should call it exports.nameOfFunction. In this case, we will call the function to send an automatic mail as exports.sendEmail:

jsx
const functions = require('firebase-functions');
const nodemailer = require('nodemailer');
const user = functions.config().gmail.user;
const pass = functions.config().gmail.pass;
const dest = functions.config().gmail.dest;
// Remember to type command before deploying → firebase functions:config:set gmail.user="EMAIL"
// Remember to type command before deploying → firebase functions:config:set gmail.pass="PASS"
// Remember to type command before deploying → firebase functions:config:set gmail.dest="DEST"

// Creating transport
const mailTransport = nodemailer.createTransport({
  service: 'gmail',
  auth: {
    user: user,
    pass: pass,
  },
});

// Sends email in case of DB change
exports.sendEmail = functions.database.ref('/posts/{pushId}/{typeOfLike}').onWrite( async (change, context) => {
    
    
    const mailOptions = {
        from: 'Erik',
        to: dest,
        subject: 'Firebase - Update ✨',
        text: `Hey! Someone gave you a ${context.params.typeOfLike.slice(0, -1)} in your ${context.params.pushId} post`
    };
    
    if(context.params.typeOfLike !== 'views') await mailTransport.sendMail(mailOptions);

    return null;
    
});

Remember to change user, pass and to with your Gmail credentials and destination mail.

Finally, deploy the new function.

shell
firebase deploy