Order children differently

[Linuus]

Hi!

I'm using awesome_nested_set today to create nested comments but looking to switch to something else but I have some questions.

Is it possible to have different ordering of nested comments? I want the root comments to be sorted with the newest first, but the rest with the newest last.

Example:

- Comment 2
  - Comment 3
    - Comment 5
    - Comment 6
  - Comment 4
- Comment 1
  - Comment 7

Today, with awesome_nested_set, I fetch all root comments and then do a separate request for each root to fetch the children.

Is there a more performant way to do it in closure_tree?

[mceachen]

Short answer: no. Have you thought about setting this order at insert time instead (by prepending to head for top level and spending to tail for lower levels) so the select "just works"?

[Linuus]

Not sure I understand what you mean.
Do you mean having a separate sort_order column and use prepend_child or prepend_sibling when creating a comment which is nested?

[mceachen]

Like this (ish)

class Comment ...
def insert(parent)
  if root? || parent.nil?
    root.prepend_sibling(self)
  else
    parent.add_child(self)

[Linuus]

Seems nice :)

And then I'd get all my comments correctly with one query?

Btw, is it possible to use pagination with closure_tree?

[Linuus]

@mceachen I did it like this

  # Comment model
  def insert
     if root? || parent.nil?
       commentable.comments.root.prepend_sibling(self)
     else
       parent.add_child(self)
     end
  end

I couldn't just do root.prepend... because root is nil.

In my controller

  # CommentsController

  def create
    # Finds the polymorphic `Commentable` (Article, BlogPost ...)
    parent = find_parent_model

    @comment = parent.comments.build(comment_params)
    @comment.user = current_user

    respond_to do |format|
      if @comment.insert
        # ....
      else
         # ....
      end
    end
  end

That should work, right?

Also, does closure_tree work have any support for pagination?

[Linuus]

That actually does not work. When I add the first comment commentable.comments.root is also nil...

[briankung]

Kind of similar: we have a Comments model as well, and we were hoping to sort by the column we use for acts_as_votable, or cached_votes_up. To our dismay, we discovered that closure_tree was overwriting the sort column with its own sort order. Is it possible to prevent this behavior? Just the behavior where CT writes over the sort order, I mean. I think it would be fine to have CT interpret cached_votes_up as the sort order, unless it wouldn't be able to handle duplicate sort order values.