渲染异构集合：如何为局部文件指定一个目录？

Question

I have a collection, @comments, that is heterogeneous but hierarchical. Each comment is either an instance of Comment or some derived class, like ActionComment or InactionComment. I am rendering a different partial for each type of Comment. The View code is:

= render @comments

As all the partials are related, I would like to keep them in a single view directory, ie:

• app/views/comments/_comment.haml
• app/views/comments/_action_comment.haml
• app/views/comments/_inaction_comment.haml

But right now in order to use the automatic rendering of the correct partial, I am using separate directories, like:

• app/views/comments/_comment.haml
• app/views/action_comments/_action_comment.haml
• app/views/inaction_comments/_inaction_comment.haml

Answer 1

Rails 3.2 makes a Model#to_partial_path method available which allows you (as its name suggests) to override the partial pathname.

  def to_partial_path
    self.action.to_s
  end

The path it returns does not include the leading underscore and is assumed to be relative to .../views/modelname/ . See http://blog.plataformatec.com.br/2012/01/my-five-favorite-hidden-features-in-rails-3-2/ for an overview

Answer 2

You can't do it quite as magically, but you can do it by just rendering each item individually and specifying the partial.

example in haml:

- @comments.each do |c|
  = render :partial => "comments/#{c.class.to_s.underscore}", :locals => {:comment => c}