Raja Tamil

Posted on Sep 27, 2021

Send Email Using Firebase Functions & Nodemailer

#firebase #javascript #programming

In this tutorial, you’re going to learn how to send an email using Firebase Functions and Nodemailer.

01. Setting Up Firebase Functions Environment

1.1 Create A Firebase Project
Go ahead and create a firebase project, if you haven’t already.

1.2 Install Firebase CLI

Firebase CLI requires Node.js so install it if you haven’t already done so.

Then, open up the Terminal / Command prompt and install Firebase CLI globally by running the following command:

npm install -g firebase-tools

Once it’s installed, go ahead and create a directory and CD to it. Then, log in to your Firebase Google Account via Terminal by running the following command:

firebase login

After that, you will be prompted with a question before opening up a browser. Hit enter, which will open up your default browser to log in.

1.3 Initialize Firebase SDK

Once you’re logged in, run the following command which will ask a few questions:

firebase init functions

Choose the newly created project among the other projects from the list.
What language would you like to use to write Cloud Functions? → Choose JavaScript, hit enter.
Do you want to use ESLint to catch probable bugs and enforce style? → choose N.
Do you want to install dependencies with npm now? (Y/N) → Yes. It will take a few seconds to complete the installation.

Once it’s installed, the new directory structure will look like this:

– firebase.json
+ functions

1.4 Install Firebase Admin SDK

Now, CD to the functions folder and run the following command:

npm install firebase-admin

Once it’s done, go to functions → index.js and import and initialize Firebase Admin SDK.

const admin = require("firebase-admin")
admin.initializeApp()

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02. Install Nodemailer Package

2.1 Install nodemailer

CD to the functions folder and run:

npm install nodemailer

Import it inside index.js file:

const nodemailer = require('nodemailer');

2.2 Create A Nodemailer Transporter

var transporter = nodemailer.createTransport({
    host: 'smtp.gmail.com',
    port: 465,
    secure: true,
    auth: {
        user: '********@gmail.com',
        pass: '************'
    }
});

This is the place where you’re going to add your SMTP information from your email hosting provider. I am using Gmail in the above example.

If you want to use a different provider, make sure to update the smtp information with yours.

Call createTransport() method passing a JavaScript object with options such as host, port, etc.

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03. Send Emails On Cloud Firestore Trigger

3.1 Declare sendEmail()

Let’s say you want to send an email to a customer every time an order is placed.

To do that, create a function named sendEmail() – it can be any name. Then, pass your Firestore database path inside the document() as an argument.

In this case, the database path is orders which is a collection. Make sure to add the wildcard {orderId} variable which will hold an actual auto-generated ID of a newly added document.

exports.sendEmail = functions.firestore
    .document('orders/{orderId}')
    .onCreate((snap, context) => {

});

I want this function to be fired when a document is created, so I am using onCreate() method. You can use onUpdate, onDelete or onWrite as well.

3.2 Invoke sendMail()

Define mailOptions with the following properties: from, to, subject and html. You can find more options here.

const mailOptions = {
    from: `softauthor1@gmail.com`,
    to: snap.data().email,
    subject: 'contact form message',
    html: `<h1>Order Confirmation</h1>
     <p> <b>Email: </b>${snap.data().email} </p>`
};

One thing worth pointing out here is that the snap.data() has information about the newly added document.

Assuming email is one of the fields in that document, I can get the value of an email field using snap.data().email.

return transporter.sendMail(mailOptions, (error, data) => {
    if (error) {
        console.log(error)
        return
    }
    console.log("Sent!")
});

Finally, call sendMail() method on transporter object by passing mailOptions as an argument.

3.3 Deploy SendMail()

Open up the Terminal and cd to the project and run:

firebase deploy --only functions

The deployment process will take a fair bit of time, which I found it too long. 🙁 Eventually, you will get the ✔ Deploy complete! message.

3.4 Test SendMail()

Create a document with a field email as a key and an actual receiver email as a value inside orders collections which will trigger the sendMail() function.

Log into a receiver email account, you should have an email.

Here is the index.js file.

const functions = require('firebase-functions');
const admin = require("firebase-admin")
const nodemailer = require('nodemailer');

admin.initializeApp()


//google account credentials used to send email
var transporter = nodemailer.createTransport({
    host: 'smtp.gmail.com',
    port: 465,
    secure: true,
    auth: {
        user: '***********@gmail.com',
        pass: 'yourpassword'
    }
});


exports.sendEmail = functions.firestore
    .document('orders/{orderId}')
    .onCreate((snap, context) => {

        const mailOptions = {
            from: `***********`,
            to: snap.data().email,
            subject: 'contact form message',
            html: `<h1>Order Confirmation</h1>
                                <p>
                                   <b>Email: </b>${snap.data().email}<br>
                                </p>`
        };


        return transporter.sendMail(mailOptions, (error, data) => {
            if (error) {
                console.log(error)
                return
            }
            console.log("Sent!")
        });
    });