Get started with firebase cloud functions

Step-1: Install packages

1.1: Install firebase-tools globally if not installed

npm i -g firebase-tools

or

yarn global add firebase-tools

Step-2: Initialize firebase

1.1: Login into your firebase account from terminal

In order to start with firebase, we need to login in google, so run the follwoing command to login

firebase login

It will output a link, click/open the link and select your google account in browser to use with this firebase project.

Note: If you are already logged in but want to switch account, just run firebase logout and then firebase login to select another account.

2.1: Select your project / Create a new one

2.1.1: Navigate to your existing project's directory / Create a new directory

2.1.2: To initialize firebase run the following command

firebase init

Go through the wizard and select Functions: Configure and deploy Cloud Functions, your project, and javascript as functions language.

2.1.3: Navigate to functions directory

cd functions

2.2: Minimum code to start with

2.2.1: Install cors to enable it

npm i cors --save

or

yarn add cors

2.2.2: Sample function body to start with

const functions = require("firebase-functions");
const admin = require("firebase-admin");
const cors = require("cors")({ origin: true });
admin.initializeApp();

exports.myCloudFunction1 = functions.https.onRequest((request, response) => {
    cors(request, response, () => {
        return new Promise(resolve => {
                    // Your code goes here

                    // Once data prepared, send response
                    response.status(200).send({
                            error: false,
                            data: 'Executed!'
                        })
                        resolve(true);
                });
        })
        .catch(err => {
            res.status(401).send(err);
        });
});

2.2.3: Sample function body with firestore

const functions = require("firebase-functions");
const admin = require("firebase-admin");
const cors = require("cors")({ origin: true });
admin.initializeApp();

exports.getAllProducts = functions.https.onRequest((request, response) => {
    cors(request, response, () => {
        return new Promise(resolve => {
            admin
                .firestore()
                .collection("products")
                .get()
                .then(querySnapshot => {
                    const products = [];
                    querySnapshot.forEach(doc => {
                        products.push({
                            id: doc.id,
                            name: doc.data()["name"]
                        });
                    });
                    response.status(200).send({
                            error: false,
                            data: products
                        })
                        resolve(true);
                });
        })
        .catch(err => {
                res.status(401).send(err);
            });
    });
});

Step-3: Serve & deploy

3.1: You can test the endpoints locally

firebase serve --only functions

3.2: Once tested, deploy

firebase deploy --only functions