Chris@909: acts_as_tree
Chris@909: ============
Chris@909: 
Chris@909: Specify this +acts_as+ extension if you want to model a tree structure by providing a parent association and a children
Chris@909: association. This requires that you have a foreign key column, which by default is called +parent_id+.
Chris@909: 
Chris@909:   class Category < ActiveRecord::Base
Chris@909:     acts_as_tree :order => "name"
Chris@909:   end
Chris@909: 
Chris@909:   Example:
Chris@909:   root
Chris@909:    \_ child1
Chris@909:         \_ subchild1
Chris@909:         \_ subchild2
Chris@909: 
Chris@909:   root      = Category.create("name" => "root")
Chris@909:   child1    = root.children.create("name" => "child1")
Chris@909:   subchild1 = child1.children.create("name" => "subchild1")
Chris@909: 
Chris@909:   root.parent   # => nil
Chris@909:   child1.parent # => root
Chris@909:   root.children # => [child1]
Chris@909:   root.children.first.children.first # => subchild1
Chris@909: 
Chris@909: Copyright (c) 2007 David Heinemeier Hansson, released under the MIT license