Getting Started with an existing Rails app

Also consult the instructions for installing on a fresh Rails app, see the React on Rails Basic Tutorial.

If you have rails-5 API only project, first convert the rails-5 API only app to rails app before getting started.

Add the following to your Gemfile and bundle install. We recommend fixing the version of React on Rails, as you will need to keep the exact version in sync with the version in your package.json file.
```
gem "react_on_rails", "12.0.0" # Update to the current version
gem "webpacker", "~> 5"
```
Add the webpacker and reacton_rails gems _Use the latest version for react_on_rails.

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

Run the following 2 commands to install Webpacker with React. Note, if you are using an older version of Rails than 5.1, you'll need to install webpacker with React per the instructions here.
```
bundle exec rails webpacker:install
bundle exec rails webpacker:install:react
```
Commit this to git (or else you cannot run the generator unless you pass the option --ignore-warnings).

See help for the generator:

$ rails generate react_on_rails:install --help

Run the generator with a simple "Hello World" example (more options below):
```
$ rails generate react_on_rails:install
```
Ensure that you have foreman installed: gem install foreman.
Start your Rails server:
```
$ foreman start -f Procfile.dev
```
Visit localhost:3000/hello_world. Note: foreman defaults to PORT 5000 unless you set the value of PORT in your environment. For example, you can export PORT=3000 to use the Rails default port of 3000. For the hello_world example this is already set.

Installation

See the Installation Overview for a concise set summary of what's in a React on Rails installation.

NPM

All JavaScript in React On Rails is loaded from npm: react-on-rails. To manually install this (you did not use the generator), assuming you have a standard configuration, run this command (assuming you are in the directory where you have your node_modules):

$ yarn add react-on-rails --exact

That will install the latest version and update your package.json. NOTE: the --exact flag will ensure that you do not have a "~" or "^" for your react-on-rails version in your package.json.