React and Flask for Side Projects

November 25th, 2018

This week, I finally got a basic version of React working with Flask. I’ve had a lot of trouble with this, not because it was technically difficult, but the overwhelming amount of choice in the JavaScript world.

Why Flask?

What I love about Flask is the same thing I love about Python: expressiveness. I felt the same kind of joy writing my first line of Python:

print 'Hello, World'

as writing my first Flask app:

from flask import Flask
app = Flask(__name__)

def hello():
	return 'Hello, World'

Both are like legos: you don’t need to read the whole manual to start playing. For the same reasons, I’ve adopted a lot of other tools like Flask-SQLAlchemy, Flask-Login, Redis. Modern apps, however, require you have a semi-thick client. Having experienced the luxuries of a good JavaScript development environment at Sentry and Numeracy, I wanted the luxuries of modern JavaScript, JSX, transpilation, and reasonable stack traces in development.

Here’s the experience I’ve wanted to have:


<h1>Regular HTML</h1>
<div id="fancy-javascript-component"></div>
<script type="text/javascript" src='app.js'></script>


class FancyComponent extends React.Component {
	render() {return <div>Encapsulating some complex behavior</div>}}

ReactDOM.render(<FancyComponent />, document.getElementById('fancy-javascript-component'))

Why not create-react-app?

The most obvious choice is create-react-app, but it was very unclear how user/session management would work, unless I planned on having a Node backend.

This then plays into the reason I use Python and specifically, Flask. It’s obvious both Python and Flask have very real limitations, but with my side projects, my greatest priority is expressiveness. I think in Python, and I don’t think that’s going to change anytime soon.

Another undesirable effect of create-react-app is…I’m suddenly building two apps: a API backend and a JS frontend. While de-coupling these two might be the “right” pattern for companies, it’s a huge pain for side projects.

I like React components, but I don’t want to start off with single page apps. 80% of my pages only need HTML/CSS, so I’d prefer to selectively add React components and over time, have a library of components that if I want to later migrate to a SPA, it’d be pretty easy.

Finding my Lego

I finally landed on Parcel. Here’s my blueprint.

 ∟ src/
    ∟ index.js
    ∟ helloMessage.jsx
    ∟ index.scss
 ∟ index.html

Note: I’m using pipenv for managing my Python environment, so the Pipfile details the dependencies.

My template index.html points to /static/dist/index.js, which imports other components. This means if more than one page requires React components, say login.html, you just need to create /static/src/login.js, and link to it in the template.

To start up the development environment:

pipenv run flask run npm run watch


I use dokku

In the post-deploy config, npm run build pipenv lock -r > requirements.txt

Tada! This is my first pass, so hopefully, I’ll be contining to update the repo as I learn more.