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React on Rails Basic Tutorial

November 11, 2020: See the example repo of React on Rails Tutorial With SSR, HMR fast refresh, and TypeScript for a new way to setup the creation of your SSR bundle with rails/webpacker. This file will be update shortly. Most of it is still relevant.

Updated for Ruby 2.7.1, Rails, and React on Rails v12.0.0

This tutorial guides you through setting up a new or existing Rails app with React on Rails, demonstrating Rails + React + Redux + Server Rendering.

After finishing this tutorial you will get an application that can do the following (live on Heroku):


You can find here:

By the time you read this, the latest may have changed. Be sure to check the versions here:

Note: some of the screen images below show the "npm" command. react_on_rails 6.6.0 and greater uses yarn.

Setting up your environment

Trying out React on Rails is super easy, so long as you have the basic prerequisites. This includes the basics for Rails 6.x and node version 13+. I recommend rvm and nvm to install Ruby and Node, and brew to install yarn. Rails can be installed as an ordinary gem.

nvm install node                # download and install latest stable Node
nvm alias default node          # make it default version
nvm list                        # check

brew install yarn               # you can use other installer if desired
rvm install 2.7                 # download and install latest stable Ruby (update to exact version)
rvm use 2.7 --default           # use it and make it default
rvm list                        # check

gem install rails               # download and install latest stable Rails
gem install foreman             # download and install Foreman

Create a new Ruby on Rails App

Then we need to create a fresh Rails application with webpacker react support as following.

First be sure to run rails -v and check you are using Rails 5.1.3 or above. If you are using an older version of Rails, you'll need to install webpacker with react per the instructions here.

cd <directory where you want to create your new Rails app>

# Any name you like for the rails app
# Skip javascript so will add that next and get the current version
rails new --skip-sprockets -J --skip-turbolinks test-react-on-rails-v12-no-sprockets

cd test-react-on-rails

Add the webpacker and react_on_rails gems

To avoid issues regarding inconsistent gem and npm versions, you should specify the exact versions of both the gem and npm package. In other words, don't use the ^ or ~ in the version specifications. Use the latest version for react_on_rails.

gem 'react_on_rails', '12.0.4'         # prefer exact gem version to match npm version

Note: The latest released React On Rails version is considered stable. Please use the latest version to ensure you get all the security patches and the best support.

bundle add webpacker                 
bundle add react_on_rails --version=12.0.4 --strict

Run the webpacker generator

bundle exec rails webpacker:install
bundle exec rails webpacker:install:react

Let's commit everything before installing React on Rails.

# Here are git commands to make a new git repo and commit everything.
# Newer versions of Rails create the git repo by default.
git add -A
git commit -m "Initial commit"

Run the React on Rails Generator

Install React on Rails: rails generate react_on_rails:install. You need to first git commit your files before running the generator, or else it will generate an error.

Note, using redux is no longer recommended as the basic installer uses React Hooks. If you want the redux install: rails generate react_on_rails:install --redux

rails generate react_on_rails:install

Then run server with a static client bundle. Static means that the bundle is saved in your public/webpack/packs directory.

foreman start -f

To run with the webpack-dev-server:

foreman start -f

Visit http://localhost:3000/hello_world and see your React On Rails app running!

HMR vs. React Hot Reloading

First, check that the hmr and the inline options are true in your config/webpacker.yml file.

The basic setup will have HMR working with the default webpacker setup. The basic HMR, without a special React setup, will cause a full page refresh each time you save a file.

Deploying to Heroku

Create Your Heroku App

Assuming you can login to and have logged into to your shell for heroku.

  1. Visit and create an app, say named my-name-react-on-rails:


Run this command that looks like this from your new heroku app

heroku git:remote -a my-name-react-on-rails

Set heroku to use multiple buildpacks:

heroku buildpacks:set heroku/ruby
heroku buildpacks:add --index 1 heroku/nodejs

Swap out sqlite for postgres by doing the following:

Run these two commands:

bundle remove sqlite3
bundle add pg


Replace your database.yml file with this (assuming your app name is "ror").

default: &default
  adapter: postgresql
  host: localhost

  <<: *default
  database: ror_development

# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
  <<: *default
  database: ror_test

  <<: *default
  database: ror_production

Then you need to setup postgres so you can run locally:

rake db:setup
rake db:migrate


I'd recommend adding this line to the top of your routes.rb. That way, your root page will go to the Hello World page for React On Rails.

root "hello_world#index"


Next, configure your app for Puma, per the instructions on Heroku.

Create /Procfile. This is what Heroku uses to start your app.


web: bundle exec puma -C config/puma.rb

Note, newer versions of Rails create this file automatically. However, the docs on Heroku have something a bit different, so please make it conform to those docs. As of 2020-06-04, the docs looked like this:


workers Integer(ENV['WEB_CONCURRENCY'] || 2)
threads_count = Integer(ENV['RAILS_MAX_THREADS'] || 5)
threads threads_count, threads_count


rackup      DefaultRackup
port        ENV['PORT']     || 3000
environment ENV['RACK_ENV'] || 'development'

on_worker_boot do
  # Worker specific setup for Rails 4.1+
  # See:

Next, update your package.json to specify the version of yarn and node. Add this section:

  "engines": {
    "node": "13.9.0",
    "yarn": "1.22.4"

Then after all changes are done don't forget to commit them with git and finally you can push your app to Heroku!

git add -A
git commit -m "Changes for Heroku"
git push heroku master

Then run:

heroku open

and you will see your live app and you can share this URL with your friends. Congrats!

Turning on Server Rendering

You can turn on server rendering by simply changing the prerender option to true:

<%= react_component("HelloWorld", props: @hello_world_props, prerender: true) %>

If you want to test this out with HMR, then you also need to add this line to your config/intializers/react_on_rails.rb

  config.same_bundle_for_client_and_server = true

More likely, you will create a different build file for server rendering. However, if you want to use the same file from the webpack-dev-server, you'll need to add that line.

Then push to Heroku:

git add -A
git commit -m "Enable server rendering"
git push heroku master

When you look at the source code for the page (right click, view source in Chrome), you can see the difference between non-server rendering, where your DIV containing your React looks like this:

<div id="HelloWorld-react-component-b7ae1dc6-396c-411d-886a-269633b3f604"></div>

versus with server rendering:

<div id="HelloWorld-react-component-d846ce53-3b82-4c4a-8f32-ffc347c8444a"><div data-reactroot=""><h3>Hello, <!-- -->Stranger<!-- -->!</h3><hr/><form><label for="name">Say hello to:</label><input type="text" id="name" value="Stranger"/></form></div></div>

For more details on server rendering, see:

ShakaCode recommends that you use /client for your client side app. This way a non-Rails, front-end developer can be at home just by opening up the /client directory.

  1. Move the directory:
mv app/javascript client
  1. Edit your /config/webpacker.yml file. Change the default/source_path:
  source_path: client

Using HMR with the rails/webpacker setup

Start the app using foreman start -f

When you change a JSX file and save, the browser will automatically refresh!

So you get some basics from HMR with no code changes. If you want to go further, take a look at these links:

React on Rails will automatically handle disabling server rendering if there is only one bundle file created by the Webpack development server by rails/webpacker.

Custom IP & PORT setup (Cloud9 example)

In case you are running some custom setup with different IP or PORT you should also edit For example to be able to run on free Cloud9 IDE we are putting IP and PORT 8080. The default generated file uses -p 3000.

web: rails s -p 8080 -b

Then visit


It's super important to exclude certain directories from RubyMine or else it will slow to a crawl as it tries to parse all the npm files.

  • Generated files, per the settings in your config/webpacker.yml, which default to public/packs and public/packs-test
  • node_modules


Feedback is greatly appreciated! As are stars on github!

If you want personalized help, don't hesitate to get in touch with us at We offer React on Rails Pro and consulting so you can focus on your app and not on how to make Webpack plus Rails work optimally.