Ever wondered how you could utilise the render method outside the context of Rails controllers and views? If you wonder why anyone would do that. Well, imagine you are building an awesome form builder, you need to output and/or store rendered partials in the buffer. How do you do that?

For example, what if you want to do this in your view?

<%=raw Awesome::FormBuilder.new(some_options).html %>

You could do something like this:

module Awesome
  class FormBuilder < AbstractController::Base
    include AbstractController::Rendering
    include ActionView::Context
    include ActionView::Helpers::CaptureHelper

    # set the view paths from your engine or from your application root, i.e. Rails.root
    self.view_paths = Awesome::Engine.root.join('app/views')

    def initialize(params)
      flush_output_buffer
      @_buffer = ''
      add_to_buffer(params)
    end

    def html
      @_buffer
    end

    private

    def add_to_buffer(params)
      # some logic to add rendered content to @_buffer
    end
  end
end

The idea is to mixin the render method, but also ensuring the view buffer is correctly reset with flush_output_buffer.

Hope that helps. :)