Decoupling GUI from API in Ruby on Rails 3

Suraj N. Kurapati

17 April 2013

config/routes.rb
app/controllers/application_controller.rb
app/controllers/users_controller.rb

Having built web applications with Rails 3 and Sencha ExtJS for the past year or so, I developed a simple way to decouple GUI concerns from APIs:

If a format is specified in the requested URI, then serve the API. Otherwise, serve the GUI while indicating that the response is non-authoritative, using HTTP status code 203.

The implementation, from routes to controllers, is demonstrated below. For example, when GET /users is requested, the GUI is served; but when GET /users.json is requested, the API is served. Similarly, when POST /users is requested, the GUI is served; but when POST /users.json is requested, the API is served and it responds with the newly created user.

config/routes.rb

# You can have the root of your site routed with "root"
# just remember to delete public/index.html.
root :to => 'application#index'

# pass unknown URLs to GUI (HTML5 history.pushState)
# http://railscasts.com/episodes/46-catch-all-route
match '*path' => 'application#index'

app/controllers/application_controller.rb

# serve GUI when no format is specified
before_filter do
  unless params[:format]
    render nothing: true, layout: true, status: :non_authoritative_information
  end
end

# serve API when a format is specified
def index
  respond_with nil, location: nil, status: :not_implemented
end
alias new     index
alias create  index
alias show    index
alias edit    index
alias update  index
alias destroy index

# serve these formats in respond_with()
respond_to :json

app/controllers/users_controller.rb

class UsersController < ApplicationController
  def create
    user = User.new(params[:user])
    respond_with(
      {
        success: !!user.save,
        errors: user.errors,
        user: user,
      },
      location: url_for(user)
    )
  end
end