Rails 3.1 How to recursively count threads belonging to a chain of forums

class Forum::Forum < ActiveRecord::Base
  belongs_to :parent_forum, :class_name => "Foru开发者_开发技巧m"
  has_many :sub_forums, :class_name => "Forum", :foreign_key => :parent_id
  has_many :threads

  def count_threads
    threads.count
  end
end

Hi I am trying to count all the threads that belong to a forum right though the chain. Currently it counts the threads that belong to the forum you're on, so if you're on forum id 1 it will count threads that belong to forum id 1 only, however forum id 1 also has sub_forums such as forum id 4 which also has a sub_forum with a id of 8 and this could go on forever.

I would really appreciate some help here, I have grand plans to build my site in rails instead of zend framework but a few little snags are keeping me stuck sometimes.

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I'd recommend taking a look at Ancestry. You should be able to get everything you need out of there if your model is what I think it is, and it can save you some code.

I believe something like @record.descendants.count should do the trick once you've integrated it.