React on Rails

React on Rails integrates Facebook's React front-end framework with Rails. Currently, both React v0.14 and v0.13 are supported. See the Rails on Maui blog post that started it all!

Be sure to see the React Webpack Rails Tutorial Code along with the live example at www.reactrails.com.

Including your React Component in your Rails Views

Please see Getting Started for how to set up your Rails project for React on Rails if you have not already done so.

• Normal Mode (React component will be rendered on client):

  <%= react_component("HelloWorldApp", @some_props) %>

• Server-Side Rendering (React component is first rendered into HTML on the server):

  <%= react_component("HelloWorldApp", @some_props, prerender: true) %>

• The component_name parameter is a string matching the name you used to globally expose your React component. So, in the above examples, if you had a React component named "HelloWorldApp," you would set window.HelloWorldApp = HelloWorldApp in your JavaScript. Exposing your component in this way is how React on Rails is able to reference your component from a Rails view. You can expose as many components as you like, as long as their names do not collide. See below for the details of how you expose your components via the react_on_rails webpack configuration.

• @some_props can be either a hash or JSON string. This is an optional argument assuming you do not need to pass any options (if you want to pass options, such as prerender: true, but you do not want to pass any properties, simply pass an empty hash {}). This will make the data available in your component:

    # Rails View
    <%= react_component("HelloWorldApp", { name: "Stranger" })

    // inside your React component
    this.props.name // "Stranger"

Documentation

• Features
• Why Webpack?
• Getting Started
• How it Works
  • Client-Side Rendering vs. Server-Side Rendering
  • Building the Bundles
  • Globally Exposing Your React Components
  • Rails View Helpers In-Depth
• Generator
  • Understanding the Organization of the Generated Client Code
  • Redux
  • Using Images and Fonts
  • Bootstrap Integration
    • Bootstrap via Rails Server
    • Bootstrap via Webpack HMR Dev Server
    • Keeping Custom Bootstrap Configurations Synced
  • Linters
    • JavaScript Linters
    • Ruby Linters
    • Running the Linters
• Developing with the Webpack Dev Server
• Adding Additional Routes for the Dev Server
• Additional Reading
• Contributing
• License
• Authors
• About ShakaCode

---

Features

Like the react-rails gem, React on Rails is capable of server-side rendering with fragment caching and is compatible with turbolinks. Unlike react-rails, which depends heavily on sprockets and jquery-ujs, React on Rails uses webpack and does not depend on jQuery. While the initial setup is slightly more involved, it allows for advanced functionality such as:

• Redux
• Webpack dev server with hot module replacement
• Webpack optimization functionality
• (Coming Soon) React Router
  • (Gem Pull Request)
  • (Tutorial Pull Request)

See the react-webpack-rails-tutorial for an example of a live implementation and code.

Why Webpack?

Webpack is used for 2 purposes:

1. Generate several JavaScript "bundles" for inclusion in application.js.
2. Providing the Webpack Dev Server for quick prototyping of components without needing to refresh your browser to see updates.

This usage of webpack fits neatly and simply into the existing Rails sprockets system and you can include React components on a Rails view with a simple helper.

Compare this to some alternative approaches for SPAs (Single Page Apps) that utilize Webpack and Rails. They will use a separate node server to distribute web pages, JavaScript assets, CSS, etc., and will still use Rails as an API server. A good example of this is our ShakaCode team member Alex's article Universal React with Rails: Part I.

We're definitely not doing that. With react_on_rails, webpack is mainly generating a nice JavaScript file for inclusion into application.js. We're going to KISS. And that's all relative given how much there is to get right in an enterprise class web application.

Getting Started

1. Add the following to your Gemfile and bundle install:

gem "react_on_rails"
gem "therubyracer"

2. Run the generator with a simple "Hello World" example:

rails generate react_on_rails:install

3. NPM install. Make sure you are on a recent version of node, preferably using nvm.

npm install

4. Start your Rails server:

foreman start -f Procfile.dev

5. Visit localhost:3000/hello_world

How it Works

The generator installs your webpack files in the client folder. Foreman uses webpack to compile your code and output the bundled results to app/assets/javascripts/generated, which are then loaded by sprockets. These generated bundle files have been added to your .gitignore for your convenience.

Inside your Rails views, you can now use the react_component helper method provided by React on Rails.

Client-Side Rendering vs. Server-Side Rendering

In most cases, you should use the prerender: false (default behavior) with the provided helper method to render the React component from your Rails views. In some cases, such as when SEO is vital or many users will not have JavaScript enabled, you can enable server-rendering by passing prerender: true to your helper, or you can simply change the default in config/initializers/react_on_rails. Your JavaScript can then be first rendered on the server and passed to the client as HTML.

Note that server-rendering requires globally exposing your components by setting them to global, not window (as is the case with client-rendering). If using the generator, you can pass the --server-rendering option to configure your application for server-side rendering.

In the following screenshot you can see the 3 parts of react_on_rails rendering:

1. Inline JavaScript to "client-side" render the React component.
2. The wrapper div <div id="HelloWorld-react-component-0"> enclosing the server-rendered HTML for the React component
3. Additional JavaScript to console log any messages, such as server rendering errors.

Note: If server rendering is not used (prerender: false), then the major difference is that the HTML rendered contains only the outer div: <div id="HelloWorld-react-component-0"/>

Building the Bundles

Each time you change your client code, you will need to re-generate the bundles (the webpack-created JavaScript files included in application.js). The included Foreman Procfile.dev will take care of this for you by watching your JavaScript code files for changes. Simply run foreman start -f Procfile.dev.

On Heroku deploys, the lib/assets.rake file takes care of running webpack during deployment. If you have used the provided generator, these bundles will automatically be added to your .gitignore in order to prevent extraneous noise from re-generated code in your pull requests. You will want to do this manually if you do not use the provided generator.

Globally Exposing Your React Components

Place your JavaScript code inside of the provided client/app folder. Use modules just as you would when using webpack alone. The difference here is that instead of mounting React components directly to an element using React.render, you expose your components globally and then mount them with helpers inside of your Rails views.

• Normal Mode (JavaScript is Rendered on client):

  If you are not server rendering, clientGlobals.jsx will have

  window.HelloWorldApp = HelloWorldApp;

• Server-Side Rendering:

  If you are server rendering, globals.jsx will have:

  window.HelloWorldApp = HelloWorldAppClient;

  serverGlobals.jsx will have:

  global.HelloWorldApp = HelloWorldAppServer;

  In general, you want different initialization for your server rendered components.

Rails View Helpers In-Depth

Once the bundled files have been generated in your app/assets/javascripts/generated folder and you have exposed your components globally, you will want to run your code in your Rails views using the included helper method.

This is how you actually render the React components you exposed to window inside of clientGlobals (and global inside of serverGlobals if you are server rendering).

react_component

react_component(component_name, props = {}, options = {})

• react_component_name: Can be a React component, created using a ES6 class, or React.createClass, or a generator function that returns a React component.
• props: Ruby Hash which contains the properties to pass to the react object, or a JSON string. If you pass a string, we'll escape it for you.
• options:
  • generator_function: default is false, set to true if you want to use a generator function rather than a React Component. Why would you do this? For example, you may want the ability to use the passed-in props to initialize a redux store or setup react-router. Or you may want to return different components depending on what's in the props.
  • prerender: enable server-side rendering of component. Set to false when debugging!
  • trace: set to true to print additional debugging information in the browser. Defaults to true for development, off otherwise.
  • replay_console: Default is true. False will disable echoing server-rendering logs to the browser. While this can make troubleshooting server rendering difficult, so long as you have the default configuration of logging_on_server set to true, you'll still see the errors on the server.
• Any other options are passed to the content tag, including the id

server_render_js

server_render_js(js_expression, options = {})

• js_expression, like 2 + 3, and not a block of js code. If you have more than one line that needs to be executed, wrap it in an IIFE. JS exceptions will be caught and console messages handled properly
• Currently the only option you may pass is replay_console (boolean)

This is a helper method that takes any JavaScript expression and returns the output from evaluating it. If you have more than one line that needs to be executed, wrap it in an IIFE. JS exceptions will be caught and console messages handled properly.

Generator

The react_on_rails:install generator combined with the example pull requests of generator runs will get you up and running efficiently. There's a fair bit of setup with integrating Webpack with Rails.

Run rails generate react_on_rails:install --help for descriptions of all available options:

Usage:
  rails generate react_on_rails:install [options]

Options:
  -R, [--redux], [--no-redux]                          # Install Redux gems and Redux version of Hello World Example
  -S, [--server-rendering], [--no-server-rendering]    # Add necessary files and configurations for server-side rendering
  -j, [--skip-js-linters], [--no-skip-js-linters]      # Skip installing JavaScript linting files
  -L, [--ruby-linters], [--no-ruby-linters]            # Install ruby linting files, tasks, and configs
  -H, [--heroku-deployment], [--no-heroku-deployment]  # Install files necessary for deploying to Heroku

Runtime options:
  -f, [--force]                    # Overwrite files that already exist
  -p, [--pretend], [--no-pretend]  # Run but do not make any changes
  -q, [--quiet], [--no-quiet]      # Suppress status output
  -s, [--skip], [--no-skip]        # Skip files that already exist

Description:
    Create react on rails files for install generator.

For a clear example of what each generator option will do, see our generator results repo: Generator Results. Each pull request shows a git "diff" that highlights the changes that the generator has made.

Understanding the Organization of the Generated Client Code

The generated client code follows our organization scheme. Each unique set of functionality, is given its own folder inside of client/app/bundles. This encourages for modularity of DOMAINS.

Inside of the generated "HelloWorld" domain you will find the following folders:

• startup: two types of files, one that return a container component and implement any code that differs between client and server code (if using server-rendering), and a clientGlobals file that exposes the aforementioned files (as well as a serverGlobals file if using server rendering). These globals files are what webpack is using as an entry point.
• containers: "smart components" (components that have functionality and logic that is passed to child "dumb components").
• components: includes "dumb components", or components that simply render their properties and call functions given to them as properties by a parent component. Ultimately, at least one of these dumb components will have a parent container component.

You may also notice the app/lib folder. This is for any code that is common between bundles and therefore needs to be shared (for example, middleware).

Redux

If you have used the --redux generator option, you will notice the familiar additional redux folders in addition to the aforementioned folders. The Hello World example has also been modified to use Redux.

Note the organizational paradigm of "bundles". These are like application domains and are used for grouping your code into webpack bundles, in case you decide to create different bundles for deployment. This is also useful for separating out logical parts of your application. The concept is that each bundle will have it's own Redux store. If you have code that you want to reuse across bundles, including components and reducers, place them under /client/app/lib.

Using Images and Fonts

The generator has amended the folders created in client/assets/ to Rails's asset path. We recommend that if you have any existing assets that you want to use with your client code, you should move them to these folders and use webpack as normal. This allows webpack's development server to have access to your assets, as it will not be able to see any assets in the default Rails directories which are above the /client directory.

Alternatively, if you have many existing assets and don't wish to move them, you could consider creating symlinks from client/assets that point to your Rails assets folders inside of app/assets/. The assets there will then be visible to both Rails and webpack.

Bootstrap Integration

React on Rails ships with Twitter Bootstrap already integrated into the build. Note that the generator removes require_tree in both the application.js and application.css.scss files. This is to ensure the correct load order for the bootstrap integration, and is usually a good idea in general. You will therefore need to explicitly require your files.

How the Bootstrap library is loaded depends upon whether one is using the Rails server or the HMR development server.

Bootstrap via Rails Server

In the former case, the Rails server loads bootstrap-sprockets, provided by the bootstrap-sass ruby gem (added automatically to your Gemfile by the generator) via the app/assets/stylesheets/_bootstrap-custom.scss partial.

This allows for using Bootstrap in your regular Rails stylesheets. If you wish to customize any of the Bootstrap variables, you can do so via the client/assets/stylesheets/_pre-bootstrap.scss partial.

Bootstrap via Webpack Dev Server

When using the webpack dev server, which does not go through Rails, bootstrap is loaded via the bootstrap-sass-loader which uses the client/bootstrap-sass-config.js file.

Keeping Custom Bootstrap Configurations Synced

Because the webpack dev server and Rails each load Bootstrap via a different file (explained in the two sections immediately above), any changes to the way components are loaded in one file must also be made to the other file in order to keep styling consistent between the two. For example, if an import is excluded in _bootstrap-custom.scss, the same import should be excluded in bootstrap-sass-config.js so that styling in the Rails server and the webpack dev server will be the same.

Linters

The React on Rails generator can add linters and their recommended accompanying configurations to your project. There are two classes of linters: ruby linters and JavaScript linters.

JavaScript Linters

JavaScript linters are enabled by default, but can be disabled by passing the --skip-js-linters flag (alias j) , and those that run in Node have been add to client/package.json under devDependencies.

Ruby Linters

Ruby linters are disabled by default, but can be enabled by passing the --ruby-linters flag when generating. These linters have been added to your Gemfile in addition to the the appropriate Rake tasks.

We really love using all the linters! Give them a try.

Running the Linters

To run the linters (runs all linters you have installed, even if you installed both Ruby and Node):

rake lint

Run this command to see all the linters available

rake -T lint

Here's the list:

rake lint               # Runs all linters
rake lint:eslint        # eslint
rake lint:js            # JS Linting
rake lint:jscs          # jscs
rake lint:rubocop[fix]  # Run Rubocop lint in shell
rake lint:ruby          # Run ruby-lint as shell
rake lint:scss          # See docs for task 'scss_lint'

Developing with the Webpack Dev Server

One of the benefits of using webpack is access to webpack's dev server and its hot module replacement functionality.

The webpack dev server with HMR will apply changes from the code (or styles!) to the browser as soon as you save whatever file you're working on. You won't need to reload the page, and your data will still be there. Start foreman as normal (it boots up the Rails server and the webpack HMR dev server at the same time).

foreman start -f Procfile.dev

Open your browser to localhost:4000. Whenever you make changes to your JavaScript code in the client folder, they will automatically show up in the browser. Hot module replacement is already enabled by default.

Note that React-related error messages are typically significantly more helpful when encountered in the dev server than the Rails server as they do not include noise added by the React on Rails gem.

Adding Additional Routes for the Dev Server

As you add more routes to your front-end application, you will need to make the corresponding API for the dev server in client/server.js. See our example server.js from our tutorial.

Additional Reading

• Generated Client Code
• Heroku Deployment
• Manual Installation
• Node Dependencies and NPM
• Optional Configuration
• Server Rendering Tips
• Tips

Contributing

Bug reports and pull requests are welcome. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to our version of the Contributor Covenant code of conduct (see CODE OF CONDUCT).

See Contributing to get started.

License

The gem is available as open source under the terms of the MIT License.

Authors

The Shaka Code team!

1. Justin Gordon
2. Samnang Chhun
3. Alex Fedoseev
4. Rob Wise
5. Blaine Hatab
6. Roger Studner
7. Aaron Van Bokhoven

And based on the work of the react-rails gem

About ShakaCode

Visit our forums!. We've got a category dedicated to react_on_rails.

If you're looking for consulting on a project using React and Rails, email us ([contact@shakacode.com](mailto: contact@shakacode.com))! You can also join our slack room for some free advice.

We're looking for great developers that want to work with Rails + React with a distributed, worldwide team, for our own products, client work, and open source. More info here.