BeforeRender Callback as concern for rails controller(s). Use it with the same syntax used for other callbacks, just include in the controller. Fires after action but before rendering happens.

before_render.rb

module BeforeRender
  extend ActiveSupport::Concern

  included do
    alias_method :render_without_before_render_action, :render
    alias_method :render, :render_with_before_render_action
    define_callbacks :render
  end

  def render_with_before_render_action(*options, &block)
    run_callbacks :render do
      render_without_before_render_action *options, &block
    end
  end

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

    def prepend_before_render_action(*names, &block)
      _insert_callbacks(names, block) do |name, options|
        set_callback :render, :before, name, options.merge(prepend: true)
      end
    end

    def skip_before_render_action(*names, &block)
      _insert_callbacks(names, block) do |name, options|
        skip_callback :render, :before, name, options
      end
    end

    alias_method :before_render, :append_before_render_action
    alias_method :prepend_before_render, :prepend_before_render_action
    alias_method :skip_before_render, :skip_before_render_action
  end
end