Jsonite in Rails using Ruby ActionView Template Handler

rb_template_template.rb

# config/initializers/rb_template_template.rb

class RbTemplateHandler
  cattr_accessor :default_format

  self.default_format = Mime::JSON

  def self.call(template)
    %{rendered = begin;#{template.source};end
      unless rendered.is_a?(String)
        rendered = rendered.to_#{template.type.to_sym}
      end
      rendered}
  end
end

ActionView::Template.register_template_handler :rb, RbTemplateHandler

show.json.rb

UserPresenter.present @user, root: 'user'