self-join eager loading recursively?

Question

I have a self-joined model:

class Comment < ActiveRecord::Base
     belongs_to :parent, :class_name => 'Comment', :foreign_key => 'parent_id'
     has_many :children, :class_name => 'Comment', :foreign_key => "parent_id"
end

Later I wish to first make 1 sql call to grab all relevant comments, and then recursively render them.

How do I recursively eager load?

comments = Comment.where(:post_id => @post_id).includes(:comments=> [:comments => [:comments .... #How do I get this to recursively eager load?

def show_comments(comment)
   render comment
   comment.children.each do |child|
       show_comments(child)
   end
end

Oh yeah, there's probably typos in the code, it's just meant to present a general idea of what i want. — Razor Storm, Jan 05 '12 at 08:08
simply put : you can't. I would advise using [awesome_nested_set](https://github.com/collectiveidea/awesome_nested_set) or [ancestry](https://github.com/stefankroes/ancestry) that are both different implementations addressing this problem (deeply nested structures on a single table) — m_x, Apr 03 '13 at 09:08

score 3 · Accepted Answer · answered Apr 17 '13 at 20:33

3

You could create a method that retrieves the deep nesting of IDs, load those, and rails will use it like a cache.

answered Apr 17 '13 at 20:33

omarvelous

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self-join eager loading recursively?

1 Answers1