acts_as_tree

Specify this +acts_as+ extension if you want to model a tree structure by providing a parent association and a children association. This requires that you have a foreign key column, which by default is called +parent_id+.

class Category < ActiveRecord::Base acts_as_tree :order => "name" end

Example: root _ child1 _ subchild1 _ subchild2

root = Category.create("name" => "root") child1 = root.children.create("name" => "child1") subchild1 = child1.children.create("name" => "subchild1")

root.parent # => nil child1.parent # => root root.children # => [child1] root.children.first.children.first # => subchild1

Copyright (c) 2007 David Heinemeier Hansson, released under the MIT license