How make Rabl works with ActionController::Metal

Rails
1

I’ve took this post
http://railsware.com/blog/2013/04/08/api-with-ruby-on-rails-useful-tricks/
like
basis but receive empty response every time. What’s wrong?

Basic controller:

class Api::V1::BaseController < ActionController::Metal
include AbstractController::Rendering
include AbstractController::Callbacks
include AbstractController::Helpers

include ActionController::HttpAuthentication::Token::ControllerMethods
include ActionController::Rendering
include ActionController::Renderers::All
include ActionController::MimeResponds
include ActionController::Instrumentation

append_view_path “#{Rails.root}/app/views”

respond_to :json
end

Controller:

class Api::V1::UsersController < Api::V1::BaseController

def index
@user = User.find(params[:id])
end
end

RABL template:

object @user

attributes :first_name