Hexagonal Rails Example

gistfile1.rb

class AddComment
  attr_reader :observer, :store, :success, :fail

  def initializer(observer, store)
    @observer, @store = observer, store
    yield self if block_given?
    return self
  end

  def call(post_id, comment_attrs)
    post = store.find(post_id)
    comment = post.add_comment(comment_attrs)
    if comment.save
      observer.success.call(post, comment)
    else
      observer.fail.call(post, comment)
    end
  end
end

class CommentController
  def create
    service = MyApp::AddComment.new(self, Post) do |service|
      service.success = on_create_success
      service.fail    = on_create_fail
    end
    service.call(post_id: 1, comment: { body: "cool!"})
  end

  private

  def on_create_success(post, comment)
    -> { |post, comment| redirect_to post }
  end

  def on_create_fail(post, comment)
    -> { |post, comment| @post, @comment = post, comment; render :new }
  end
end

I like the idea of passing the store to the service object. I forked this gist and updated it to use the Wisper gem for the observer part, here is the diff.

If your interested there are other examples on the wiki 😄