react_on_rails.rb

module RenderingExtension
  # Return a Hash that contains custom values from the view context that will get passed to
  # all calls to react_component and redux_store for rendering
  def self.custom_context(view_context)
    if view_context.controller.is_a?(ActionMailer::Base)
      {}
    else
      {
        somethingUseful: view_context.session[:something_useful]
      }
    end
  end
end

ReactOnRails.configure do |config|
  # Directory where your generated assets go. All generated assets must go to the same directory.
  # Configure this in your webpack config files. This relative to your Rails root directory.
  config.generated_assets_dir = File.join(%w(app assets webpack))

  # Define the files we need to check for webpack compilation when running tests.
  config.webpack_generated_files = %w(app-bundle.js vendor-bundle.js server-bundle.js)

  # This is the file used for server rendering of React when using `(prerender: true)`
  # If you are never using server rendering, you may set this to "".
  # If you are using the same file for client and server rendering, having this set probably does
  # not affect performance.
  config.server_bundle_js_file = "server-bundle.js"

  # If you are using the ReactOnRails::TestHelper.configure_rspec_to_compile_assets(config)
  # with rspec then this controls what npm command is run
  # to automatically refresh your webpack assets on every test run.
  config.npm_build_test_command = "npm run build:test"

  # This configures the script to run to build the production assets by webpack. Set this to nil
  # if you don't want react_on_rails building this file for you.
  config.npm_build_production_command = "npm run build:production"

  ################################################################################
  # CLIENT RENDERING OPTIONS
  # Below options can be overriden by passing options to the react_on_rails
  # `render_component` view helper method.
  ################################################################################
  # default is false
  config.prerender = false

  # default is true for development, off otherwise
  config.trace = Rails.env.development?

  ################################################################################
  # SERVER RENDERING OPTIONS
  ################################################################################

  # If set to true, this forces Rails to reload the server bundle if it is modified
  config.development_mode = Rails.env.development?

  # For server rendering. This can be set to false so that server side messages are discarded.
  # Default is true. Be cautious about turning this off.
  config.replay_console = true

  # Default is true. Logs server rendering messages to Rails.logger.info
  config.logging_on_server = true

  config.raise_on_prerender_error = false # change to true to raise exception on server if the JS code throws

  # Server rendering only (not for render_component helper)
  # You can configure your pool of JS virtual machines and specify where it should load code:
  # On MRI, use `mini_racer` for the best performance
  # (see [discussion](https://github.com/reactjs/react-rails/pull/290))
  # 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.
  config.server_renderer_pool_size = 1 # increase if you're on JRuby
  config.server_renderer_timeout = 20 # seconds

  ################################################################################
  # MISCELLANEOUS OPTIONS
  ################################################################################
  # Default is false, enable if your content security policy doesn't include `style-src: 'unsafe-inline'`
  config.skip_display_none = false

  # This allows you to add additional values to the Rails Context. Implement one static method
  # called `custom_context(view_context)` and return a Hash.
  config.rendering_extension = RenderingExtension

  # The server render method - either ExecJS or NodeJS
  config.server_render_method = "ExecJS"

  # Client js uses assets not digested by rails.
  # For any asset matching this regex, a file is copied to the correct path to have a digest.
  # To disable creating digested assets, set this parameter to nil.
  config.symlink_non_digested_assets_regex = /\.(png|jpg|jpeg|gif|tiff|woff|ttf|eot|svg|map)/
end