---

react-rails

react-rails makes it easy to use React and JSX in your Ruby on Rails (3.2+) application. react-rails can:

• Provide various react builds to your asset bundle
• Transform .jsx in the asset pipeline
• Render components into views and mount them via view helper & react_ujs
• Render components server-side with prerender: true
• Generate components with a Rails generator

Installation

Add react-rails to your gemfile:

gem 'react-rails', '~> 1.0'

Next, run the installation script:

rails g react:install

This will:

• create a components.js manifest file and a app/assets/javascripts/components/ directory, where you will put your components

• place the following in your application.js:

  //= require react
  //= require react_ujs
  //= require components

Usage

React.js builds

You can pick which React.js build (development, production, with or without add-ons) to serve in each environment by adding a config. Here are the defaults:

# config/environments/development.rb
MyApp::Application.configure do
  config.react.variant = :development
end

# config/environments/production.rb
MyApp::Application.configure do
  config.react.variant = :production
end

To include add-ons, use this config:

MyApp::Application.configure do
  config.react.addons = true # defaults to false
end

After restarting your Rails server, //= require react will provide the build of React.js which was specified by the configurations.

react-rails offers a few other options for versions & builds of React.js. See VERSIONS.md for more info about using the react-source gem or dropping in your own copies of React.js.

JSX

After installing react-rails, restart your server. Now, .js.jsx files will be transformed in the asset pipeline.

react-rails currently ships with two transformers, to convert jsx code -

• BabelTransformer using Babel, which is the default transformer.
• JSXTransformer using JSXTransformer.js

You can use the deprecated JSXTransformer by setting it in an application config:

  config.react.jsx_transformer_class = React::JSX::JSXTransformer

BabelTransformer options

You can use babel's transformers and custom plugins, and pass options to the babel transpiler adding following configurations:

config.react.jsx_transform_options = {
  blacklist: ['spec.functionName', 'validation.react'], # default options
  optional: ["transformerName"],  # pass extra babel options
  whitelist: ["useStrict"] # even more options
}

Under the hood, react-rails uses ruby-babel-transpiler, for transformation.

JSXTransformer options

You can use JSX --harmony or --strip-types options by adding a configuration:

config.react.jsx_transform_options = {
  harmony: true,
  strip_types: true, # for removing Flow type annotations
  asset_path: "path/to/JSXTransformer.js", # if your JSXTransformer is somewhere else
}

Rendering & mounting

react-rails includes a view helper (react_component) and an unobtrusive JavaScript driver (react_ujs) which work together to put React components on the page. You should require the UJS driver in your manifest after react (and after turbolinks if you use Turbolinks).

The view helper puts a div on the page with the requested component class & props. For example:

<%= react_component('HelloMessage', name: 'John') %>
<!-- becomes: -->
<div data-react-class="HelloMessage" data-react-props="{&quot;name&quot;:&quot;John&quot;}"></div>

On page load, the react_ujs driver will scan the page and mount components using data-react-class and data-react-props.

If Turbolinks is present components are mounted on the page:change event, and unmounted on page:before-unload. Turbolinks >= 2.4.0 is recommended because it exposes better events.

The view helper's signature is:

react_component(component_class_name, props={}, html_options={})

• component_class_name is a string which names a globally-accessible component class. It may have dots (eg, "MyApp.Header.MenuItem").
• props is either an object that responds to #to_json or an already-stringified JSON object (eg, made with Jbuilder, see note below).
• html_options may include:
  • tag: to use an element other than a div to embed data-react-class and -props.
  • prerender: true to render the component on the server.
  • **other Any other arguments (eg class:, id:) are passed through to content_tag.

Server rendering

To render components on the server, pass prerender: true to react_component:

<%= react_component('HelloMessage', {name: 'John'}, {prerender: true}) %>
<!-- becomes: -->
<div data-react-class="HelloMessage" data-react-props="{&quot;name&quot;:&quot;John&quot;}">
  <h1>Hello, John!</h1>
</div>

(It will be also be mounted by the UJS on page load.)

There are some requirements for this to work:

• react-rails must load your code. By convention it uses components.js, which was created by the install task. This file must include your components and their dependencies (eg, Underscore.js).

• Your components must be accessible in the global scope. If you are using .js.jsx.coffee files then the wrapper function needs to be taken into account:

  # @ is `window`:
  @Component = React.createClass
    render: ->
      `<ExampleComponent videos={this.props.videos} />`

• Your code can't reference document. Prerender processes don't have access to document, so jQuery and some other libs won't work in this environment :(

You can configure your pool of JS virtual machines and specify where it should load code:

# config/environments/application.rb
# These are the defaults if you dont specify any yourself
MyApp::Application.configure do
  # Settings for the pool of renderers:
  config.react.server_renderer_pool_size  ||= 1  # ExecJS doesn't allow more than one on MRI
  config.react.server_renderer_timeout    ||= 20 # seconds
  config.react.server_renderer = React::ServerRendering::SprocketsRenderer
  config.react.server_renderer_options = {
    files: ["react.js", "components.js"], # files to load for prerendering
    replay_console: true,                 # if true, console.* will be replayed client-side
  }
end

• On MRI, use therubyracer for the best performance (see discussion)
• On MRI, you'll get a deadlock with pool_size > 1
• If you're using JRuby, you can increase pool_size to have real multi-threaded rendering.

Component generator

react-rails ships with a Rails generator to help you get started with a simple component scaffold. You can run it using rails generate react:component ComponentName (--es6). The generator takes an optional list of arguments for default propTypes, which follow the conventions set in the Reusable Components section of the React documentation.

For example:

rails generate react:component Post title:string body:string published:bool published_by:instanceOf{Person}

would generate the following in app/assets/javascripts/components/post.js.jsx:

var Post = React.createClass({
  propTypes: {
    title: React.PropTypes.string,
    body: React.PropTypes.string,
    published: React.PropTypes.bool,
    publishedBy: React.PropTypes.instanceOf(Person)
  },

  render: function() {
    return (
      <div>
        <div>Title: {this.props.title}</div>
        <div>Body: {this.props.body}</div>
        <div>Published: {this.props.published}</div>
        <div>Published By: {this.props.publishedBy}</div>
      </div>
    );
  }
});

Options

--es6 : Generate the same component but using cutting edge es6 class

For example:

rails generate react:component Label label:string --es6

Arguments

The generator can use the following arguments to create basic propTypes:

• any
• array
• bool
• element
• func
• number
• object
• node
• shape
• string

The following additional arguments have special behavior:

• instanceOf takes an optional class name in the form of {className}.
• oneOf behaves like an enum, and takes an optional list of strings in the form of 'name:oneOf{one,two,three}'.
• oneOfType takes an optional list of react and custom types in the form of 'model:oneOfType{string,number,OtherType}'.

Note that the arguments for oneOf and oneOfType must be enclosed in single quotes to prevent your terminal from expanding them into an argument list.

Jbuilder & react-rails

If you use Jbuilder to pass a JSON string to react_component, make sure your JSON is a stringified hash, not an array. This is not the Rails default -- you should add the root node yourself. For example:

# BAD: returns a stringified array
json.array!(@messages) do |message|
  json.extract! message, :id, :name
  json.url message_url(message, format: :json)
end

# GOOD: returns a stringified hash
json.messages(@messages) do |message|
  json.extract! message, :id, :name
  json.url message_url(message, format: :json)
end

CoffeeScript

It is possible to use JSX with CoffeeScript. To use CoffeeScript, create files with an extension .js.jsx.coffee. We also need to embed JSX code inside backticks so that CoffeeScript ignores the syntax it doesn't understand. Here's an example:

Component = React.createClass
  render: ->
    `<ExampleComponent videos={this.props.videos} />`