React-Rails

React-Rails is a flexible tool to use React with Rails. It:

Automatically renders React server-side and client-side
Supports Webpacker 3.x, 2.x, 1.1+
Supports Sprockets 4.x, 3.x, 2.x
Lets you use JSX, ES6, Coffeescript

Example app code available here: https://github.com/BookOfGreg/react-rails-example-app

Get started with Webpacker
- File naming
Use with Asset Pipeline
- Custom JSX Transformer
- React.js versions
View Helper
- Custom View Helper
UJS
Server-Side Rendering
Controller Actions
Component Generator
- Use with JBuilder
- Camelize Props
Upgrading
- 2.3 to 2.4
Related Projects
Contributing

The React-Rails Wiki has lots of additional information about React-Rails including many "how-to" articles and answers to the most frequently asked questions. Please browse the Wiki after finishing this README:

https://github.com/reactjs/React-Rails/wiki

Get started with Webpacker

or Get started with Sprockets

Webpacker integrates modern JS tooling with Rails.

Add webpacker and react-rails to your gemfile and run the installers:

$ bundle install
$ rails webpacker:install       # OR (on rails version < 5.0) rake webpacker:install
$ rails webpacker:install:react # OR (on rails version < 5.0) rake webpacker:install:react
$ rails generate react:install

This gives you:

app/javascript/components/ directory for your React components
ReactRailsUJS setup in app/javascript/packs/application.js
app/javascript/packs/server_rendering.js for server-side rendering

Link the JavaScript pack in Rails view using javascript_pack_tag helper, for example:

<!-- application.html.erb -->
<%= javascript_pack_tag 'application' %>

Generate your first component:

$ rails g react:component HelloWorld greeting:string

Your component is added to app/javascript/components/ by default.

Render it in a Rails view:

<%= react_component("HelloWorld", { greeting: "Hello" }) %>

The component name tells react-rails where to load the component. For example:

`react_component` call	component `require`
`react_component("Item")`	`require("Item")`
`react_component("items/index")`	`require("items/index")`
`react_component("items.Index")`	`require("items").Index`
`react_component("items.Index.Header")`	`require("items").Index.Header`

This way, you can access top-level, default, or named exports.

The require.context inserted into packs/application.js is used to load components. If you want to load components from a different directory, override it by calling ReactRailsUJS.useContext:

var myCustomContext = require.context("custom_components", true)
var ReactRailsUJS = require("react_ujs")
// use `custom_components/` for <%= react_component(...) %> calls
ReactRailsUJS.useContext(myCustomContext)

If require fails to find your component, ReactRailsUJS falls back to the global namespace, described in Use with Asset Pipeline.

File naming

React-Rails supports plenty of file extensions such as: .js, .jsx.js, .js.jsx, .es6.js, .coffee, etcetera! Sometimes this will cause a stumble when searching for filenames.

Component File Name	`react_component` call
`app/javascript/components/samplecomponent.js`	`react_component("samplecomponent")`
`app/javascript/components/sample_component.js`	`react_component("sample_component")`
`app/javascript/components/SampleComponent.js`	`react_component("SampleComponent")`
`app/javascript/components/SampleComponent.js.jsx`	Has to be renamed to SampleComponent.jsx, then use `react_component("SampleComponent")`

Typescript support

If you want to use React-Rails with Typescript, simply run the installer and add @types:

$ bundle exec rails webpacker:install:typescript
$ yarn add @types/react @types/react-dom

Doing this will allow React-Rails to support the .tsx extension.

Use with Asset Pipeline

react-rails provides a pre-bundled React.js & a UJS driver to the Rails asset pipeline. Get started by installing:

$ rails g react:install

Then restart your development server.

This will:

add some //= requires to application.js
add a components/ directory for React components
add server_rendering.js for server-side rendering

Now, you can create React components in .jsx files:

// app/assets/javascripts/components/post.jsx

window.Post = createReactClass({
  render: function() {
    return <h1>{this.props.title}</h1>
  }
})

// or, equivalent:
class Post extends React.Component {
  render() {
    return <h1>{this.props.title}</h1>
  }
}

Then, you can render those components in views:

<%= react_component("Post", {title: "Hello World"}) %>

Components must be accessible from the top level, but they may be namespaced, for example:

<%= react_component("Comments.NewForm", {post_id: @post.id}) %>
<!-- looks for `window.Comments.NewForm` -->

Custom JSX Transformer

react-rails uses a transformer class to transform JSX in the asset pipeline. The transformer is initialized once, at boot. You can provide a custom transformer to config.react.jsx_transformer_class. The transformer must implement:

#initialize(options), where options is the value passed to config.react.jsx_transform_options
#transform(code_string) to return a string of transformed code

react-rails provides two transformers, React::JSX::BabelTransformer (which uses ruby-babel-transpiler) and React::JSX::JSXTransformer (which uses the deprecated JSXTransformer.js).

React.js versions

//= require react brings React into your project.

By default, React's [development version] is provided to Rails.env.development. You can override the React build with 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

Be sure to restart your Rails server after changing these files. See VERSIONS.md to learn which version of React.js is included with your react-rails version. In some edge cases you may need to bust the sprockets cache with rake tmp:clear

View Helper

react-rails includes a view helper and an unobtrusive JavaScript driver which work together to put React components on the page.

The view helper (react_component) 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.

The view helper's signature is:

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

component_class_name is a string which identifies a component. See getConstructor for details.
props is either:
- an object that responds to #to_json; or
- an already-stringified JSON object (see JBuilder note below).
html_options may include:
- tag: to use an element other than a div to embed data-react-class and data-react-props.
- prerender: true to render the component on the server.
- camelize_props to transform a props hash
- **other Any other arguments (eg class:, id:) are passed through to content_tag.

Custom View Helper

react-rails uses a "helper implementation" class to generate the output of the react_component helper. The helper is initialized once per request and used for each react_component call during that request. You can provide a custom helper class to config.react.view_helper_implementation. The class must implement:

#react_component(name, props = {}, options = {}, &block) to return a string to inject into the Rails view
#setup(controller_instance), called when the helper is initialized at the start of the request
#teardown(controller_instance), called at the end of the request

react-rails provides one implementation, React::Rails::ComponentMount.

UJS

react-rails's JavaScript is available as "react_ujs" in the asset pipeline or from NPM. It attaches itself to the window as ReactRailsUJS.

Mounting & Unmounting

Usually, react-rails mounts & unmounts components automatically as described in Event Handling below.

You can also mount & unmount components from <%= react_component(...) %> tags using UJS:

// Mount all components on the page:
ReactRailsUJS.mountComponents()
// Mount components within a selector:
ReactRailsUJS.mountComponents(".my-class")
// Mount components within a specific node:
ReactRailsUJS.mountComponents(specificDOMnode)

// Unmounting works the same way:
ReactRailsUJS.unmountComponents()
ReactRailsUJS.unmountComponents(".my-class")
ReactRailsUJS.unmountComponents(specificDOMnode)

You can use this when the DOM is modified by AJAX calls or modal windows.

Event Handling

ReactRailsUJS checks for various libraries to support their page change events:

Turbolinks
pjax
jQuery
Native DOM events

ReactRailsUJS will automatically mount components on <%= react_component(...) %> tags and unmount them when appropriate.

If you need to re-detect events, you can call detectEvents:

// Remove previous event handlers and add new ones:
ReactRailsUJS.detectEvents()

For example, if Turbolinks is loaded after ReactRailsUJS, you'll need to call this again. This function removes previous handlers before adding new ones, so it's safe to call as often as needed.

`getConstructor`

Components are loaded with ReactRailsUJS.getConstructor(className). This function has two built-in implementations:

On the asset pipeline, it looks up className in the global namespace.
On Webpacker, it requires files and accesses named exports, as described in Use with Webpacker.

You can override this function to customize the mapping of name-to-constructor. Server-side rendering also uses this function.

Server-Side Rendering

You can render React components inside your Rails server with prerender: true:

<%= 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 also be mounted by the UJS on page load.)

Server rendering is powered by ExecJS and subject to some requirements:

react-rails must load your code. By convention, it uses server_rendering.js, which was created by the install task. This file must include your components and their dependencies (eg, Underscore.js).
Your code can't reference document or window. Prerender processes don't have access to document or window, so jQuery and some other libs won't work in this environment :(

ExecJS supports many backends. CRuby users will get the best performance from mini_racer.

Configuration

Server renderers are stored in a pool and reused between requests. Threaded Rubies (eg jRuby) may see a benefit to increasing the pool size beyond the default 0.

These are the default configurations:

# config/application.rb
# These are the defaults if you don't specify any yourself
module MyApp
  class Application < Rails::Application
    # 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::BundleRenderer
    config.react.server_renderer_options = {
      files: ["server_rendering.js"],       # files to load for prerendering
      replay_console: true,                 # if true, console.* will be replayed client-side
    }
    # Changing files matching these dirs/exts will cause the server renderer to reload:
    config.react.server_renderer_extensions = ["jsx", "js"]
    config.react.server_renderer_directories = ["/app/assets/javascripts", "/app/javascript/"]
  end
end

JavaScript State

Some of ExecJS's backends are stateful (eg, mini_racer, therubyracer). This means that any side-effects of a prerender will affect later renders with that renderer.

To manage state, you have a couple options:

Make a custom renderer with #before_render / #after_render hooks as described below
Use per_request_react_rails_prerenderer to manage state for a whole controller action.

To check out a renderer for the duration of a controller action, call the per_request_react_rails_prerenderer helper in the controller class:

class PagesController < ApplicationController
  # Use the same React server renderer for the entire request:
  per_request_react_rails_prerenderer
end

Then, you can access the ExecJS context directly with react_rails_prerenderer.context:

def show
  react_rails_prerenderer           # => #<React::ServerRendering::BundleRenderer>
  react_rails_prerenderer.context   # => #<ExecJS::Context>

  # Execute arbitrary JavaScript code
  # `self` is the global context
  react_rails_prerenderer.context.exec("self.Store.setup()")
  render :show
  react_rails_prerenderer.context.exec("self.Store.teardown()")
end

react_rails_prerenderer may also be accessed in before- or after-actions.

Custom Server Renderer

react-rails depends on a renderer class for rendering components on the server. You can provide a custom renderer class to config.react.server_renderer. The class must implement:

#initialize(options={}), which accepts the hash from config.react.server_renderer_options
#render(component_name, props, prerender_options) to return a string of HTML

react-rails provides two renderer classes: React::ServerRendering::ExecJSRenderer and React::ServerRendering::BundleRenderer.

ExecJSRenderer offers two other points for extension:

#before_render(component_name, props, prerender_options) to return a string of JavaScript to execute before calling React.render
#after_render(component_name, props, prerender_options) to return a string of JavaScript to execute after calling React.render

Any subclass of ExecJSRenderer may use those hooks (for example, BundleRenderer uses them to handle console.* on the server).

Controller Actions

Components can also be server-rendered directly from a controller action with the custom component renderer. For example:

class TodoController < ApplicationController
  def index
    @todos = Todo.all
    render component: 'TodoList', props: { todos: @todos }, tag: 'span', class: 'todo'
  end
end

You can also provide the "usual" render arguments: content_type, layout, location and status. By default, your current layout will be used and the component, rather than a view, will be rendered in place of yield. Custom data-* attributes can be passed like data: {remote: true}.

Prerendering is set to true by default, but can be turned off with prerender: false.

Component Generator

You can generate a new component file with:

rails g react:component ComponentName prop1:type prop2:type ...

For example,

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

would generate:

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

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

The generator also accepts options:

--es6: use class ComponentName extends React.Component
--coffee: use CoffeeScript

Accepted PropTypes are:

Plain types: any, array, bool, element, func, number, object, node, shape, string
instanceOf takes an optional class name in the form of instanceOf{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.

Use with JBuilder

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

Camelize Props

You can configure camelize_props option:

MyApp::Application.configure do
  config.react.camelize_props = true # default false
end

Now, Ruby hashes given to react_component(...) as props will have their keys transformed from underscore- to camel-case, for example:

{ all_todos: @todos, current_status: @status }
# becomes:
{ "allTodos" => @todos, "currentStatus" => @status }

You can also specify this option in react_component:

<%= react_component('HelloMessage', {name: 'John'}, {camelize_props: true}) %>

Upgrading

2.3 to 2.4

Keep your react_ujs up to date, yarn upgrade

React-Rails 2.4.x uses React 16+ which no longer has React Addons. Therefore the pre-bundled version of react no longer has an addons version, if you need addons still, there is the 2.3.1+ version of the gem that still has addons.

If you need to make changes in your components for the prebundled react, see the migration docs here:

For the vast majority of cases this will get you most of the migration:

global find+replace React.Prop -> Prop
add import PropTypes from 'prop-types' (Webpacker only)
re-run bundle exec rails webpacker:install:react to update npm packages (Webpacker only)

Related Projects

webpacker-react: Integration of React with Rails utilizing Webpack with Hot Module Replacement (HMR).
The Free React on Rails Course A free video course which teaches the basics of React and how to get started using it in Rails with react-rails.
react_on_rails: Integration of React with Rails utilizing Webpack, Redux, React-Router.
react-rails-hot-loader Simple live-reloader for react-rails.
react-rails-benchmark_renderer adds performance instrumentation to server rendering.
Ruby Hyperloop: Use Ruby to build reactive user interfaces with React.

Contributing

🎉 Thanks for taking the time to contribute! 🎉

With 2 Million+ downloads of the react-rails Gem and another 100k+ downloads of react_ujs on NPM, you're helping the biggest React + Rails community!

By contributing to React-Rails, you agree to abide by the code of conduct.

You can always help by submitting patches or triaging issues, even offering reproduction steps to issues is incredibly helpful!

Please see our Contribution guide for more info.

diegoazd/react-rails