Modular APIs with Grape and Rails

api.rb

class API < Grape::API
  format :json
  error_format :json

  version 'v1', :using => :header, :vendor => "App"

  rescue_from Mongoid::Errors::DocumentNotFound do |error|
    rack_response({"error" => {"message" => "We didn't find what we were looking for"}}.to_json, 404)
  end

  mount Users::APIV1
end

apiv1.rb

module Users
  class APIV1 < Grape::API

    resource :user do
      desc "Returns a user for a given user id"
      get '/:id' do
        user = User.find(params[:id])
        present user, :with => Users::UserResponseEntity
      end
    end
  
  end
end

contact_info_response_entity.rb

module Users
  class ContactInfoResponseEntity < Grape::Entity

    expose :address_line
    expose :city
    expose :country
    expose :zipcode
    expose :state
    expose :phone_numbers, :using => Users::PhoneNumberResponseEntity

  end
end

phone_number_response_entity.rb

module Users
  class PhoneNumberResponseEntity < Grape::Entity

    expose :country_code
    expose :area_code
    expose :number
    expose :formatted_number

  end
end

user_response_entity.rb

module Users
  class UserResponseEntity < Grape::Entity

    expose :first_name
    expose :last_name
    expose :formatted_name, :as => "full_name"
    expose :username
    expose :email
    expose :contact_info, :using => Users::ContactInfoResponseEntity

  end
end