Adding React to Rails

Learning Goals

Use create-react-app to generate a new React application within a Rails project
Proxy requests from React to Rails in development
Use the foreman gem to run React and Rails together

Introduction

In the last lesson, we created a Rails API from scratch. Now it's time to see how we can add a React frontend application as well.

There are a number of ways to use React and Rails together, such as using the webpacker gem to manage JavaScript as part of your Rails application. However, we like the simplicity and the tooling that you get out of using create-react-app to generate a new React application within Rails. If you've used create-react-app before, you should feel right at home! We can also add a few additional tools to the process to make running React and Rails together a bit easier.

Generating a React Application

To get started, let's spin up our React application using create-react-app:

$ npx create-react-app client --use-npm

This will create a new React application in a client folder, and will use npm instead of yarn to manage our dependencies.

When we're running React and Rails in development, we'll need two separate servers running on different ports — we'll run React on port 4000, and Rails on port 3000. Whenever we want to make a request to our Rails API from React, we'll need to make sure that our requests are going to port 3000.

We can simplify this process of making requests to the correct port by using create-react-app in development to proxy the requests to our API. This will let us write our network requests like this:

fetch("/movies");
// instead of fetch("http://localhost:3000/movies")

To set up this proxy feature, open the package.json file in the client directory and add this line at the top level of the JSON object:

"proxy": "http://localhost:3000"

Let's also update the "start" script in the the package.json file to specify a different port to run our React app in development:

"scripts": {
  "start": "PORT=4000 react-scripts start"
}

With that set up, let's try running our servers! In your terminal, run Rails:

$ rails s

Then, open a new terminal, and run React:

$ npm start --prefix client

This will run npm start in the client directory. Verify that your app is working by visiting:

http://localhost:4000 to view the React application
http://localhost:3000/movies to view the Rails application

We can also see how to make a request using fetch. In the React application, update your App.js file with the following code:

import { useEffect } from "react";

function App() {
  useEffect(() => {
    fetch("/movies")
      .then((r) => r.json())
      .then((movies) => console.log(movies));
  }, []);

  return <h1>Hello from React!</h1>;
}

export default App;

This will use the useEffect hook to fetch data from our Rails API, which you can then view in the console.

Running React and Rails Together

Since we'll often want to run our React and Rails applications together, it can be helpful to be able to run them from just one command in the terminal instead of opening multiple terminals.

To facilitate this, we'll use the excellent foreman gem. Install it:

$ gem install foreman

Foreman works with a special kind of file known as a Procfile, which lists different processes to run for our application. Some hosting services, such as Heroku, use a Procfile to run applications, so by using a Procfile in development as well, we'll simplify the deploying process later.

In the root directory, create a file Procfile.dev and add this code:

web: PORT=4000 npm start --prefix client
api: PORT=3000 rails s

Then, run it with Foreman:

$ foreman start -f Procfile.dev

This will start both React and Rails on separate ports, just like before; but now we can run both with one command!

There is one big caveat to this approach: by running our client and server in the same terminal, it can be more challenging to read through the server logs and debug our code. Furthermore, byebug will not work. If you're doing a lot of debugging in the terminal, you should run the client and server separately to get a cleaner terminal output and allow terminal-based debugging with byebug.

You can run each application separately by opening two terminal windows and running each of these commands in a separate window:

$ npm start --prefix client
$ rails s

This will run React on port 4000 (thanks to the configuration in the client/package.json file), and Rails on port 3000 (the default port).

Conclusion

In the past couple lessons, we've seen how to put together the two pieces we'll need for full-stack applications by using rails new to create a new Rails API, and create-react-app to create a React project. Throughout the rest of this module, we'll focus on how our two applications communicate and share data.

Check For Understanding

Before you move on, make sure you can answer the following questions:

What options do you have for running Rails and React at the same time?
What are the advantages and disadvantages of using foreman as described in this lesson?

Resources

Proxying API Requests in Create React App

bobby-bates / phase-4-adding-react-to-rails