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Sample Function: QR Code Generator

Introduction

This repository contains a sample QR code generator function. You can deploy it on DigitalOcean's App Platform as a Serverless Function component. Documentation is available at https://docs.digitalocean.com/products/functions.

Requirements

• You need a DigitalOcean account. If you don't already have one, you can sign up at https://cloud.digitalocean.com/registrations/new.
• To deploy from the command line, you will need the DigitalOcean doctl CLI.

Deploying the Function

# clone this repo
git clone git@github.com:digitalocean/sample-functions-nodejs-qrcode.git

# deploy the project
> doctl serverless deploy sample-functions-nodejs-qrcode
Deploying 'sample-functions-nodejs-qrcode'
  to namespace 'fn-...'
  on host 'https://faas-...'
Started running npm install --production in sample-functions-nodejs-qrcode/default/qr
Finished running npm install --production in sample-functions-nodejs-qrcode/default/qr
...

Deployed functions ('doctl sbx fn get <funcName> --url' for URL):
  - qr

Using the Function

> doctl serverless functions invoke qr/qr -p text:hello
{
  "body": "data:image/png;base64,iVB...5CYII=",
  "headers": {
    "content-type": "text/html; charset=UTF-8"
  }
}

Project File Structure

This app is a stateless single-page web application that generates a QR code from text that a user submits.

This project has the following components:

• A single index.html file, which has a field for a visitor to enter some text and click Submit.
• A single JavaScript file qr.js that provides the backend logic for the conversion of text to QR code.
• A Node package manager file called package.json, which describes what dependencies the function has.

The GitHub project has the file structure that App Platform uses to intelligently deploy the project:

• The packages directory contains the project's API implementation, and in this example, there's only one API implemented by a single function. The first subdirectory name usually serves as the package qualifier. The next subdirectory, qr, is the name of the function, and the file qr.js contains the logic for that function. The qualified name of the function is also the name of the API it implements which is default/qr in this case.
• The client directory contains the static web content for the project. In this case, there is just one HTML file and one image. The index.html file contains a form with a text box for the user to input the text that will be converted.

Notes on QR Logic

The code for the QR action is standard Node.js. It uses an existing Node library package for the actual QR code generation.

Notes on QR Web Content

The index.html file contains the usual markup and logic that you'd write for standard web deployment, with an input form for text. In this case, it calls an API to retrieve a QR code for the form input. This API is implemented by qr.js.

Notes on package.json

The package.json file in the qr directory triggers an automatic build of the action when the function in qr.js is modified.

Learn More

You can learn more about Functions and App Platform integration in the official App Platform Documentation.