before_render.rb

module BeforeRender
  extend ActiveSupport::Concern

  included do
    define_callbacks :render
  end

  def render(*args, &block)
    run_callbacks(:render) do
      super
    end
  end

  module ClassMethods
    def before_render(*names, &blk)
      _insert_callbacks(names, blk) do |name, options|
        set_callback(:render, :before, name, options)
      end
    end
  end
end