def dom_id(record, prefix = nil)
      if record_id = record_key_for_dom_id(record)
        "#{dom_class(record, prefix)}#{JOIN}#{record_id}"
      else
        dom_class(record, prefix || NEW)
      end
    end
def dom_id(record, prefix = nil)
      if record_id = record_key_for_dom_id(record)
        "#{dom_class(record, prefix)}#{JOIN}#{record_id}"
      else
        dom_class(record, prefix || NEW)
      end
    end
The DOM id convention is to use the singular form of an object or class with the id following an underscore.
 If no id is found, prefix with "new_" instead.

   dom_id(Post.find(45))       # => "post_45"
   dom_id(Post.new)            # => "new_post"

 If you need to address multiple instances of the same class in the same view, you can prefix the dom_id:

   dom_id(Post.find(45), :edit) # => "edit_post_45"
   dom_id(Post.new, :custom)    # => "custom_post"