Chris@909: = AwesomeNestedSet
Chris@909: 
Chris@909: Awesome Nested Set is an implementation of the nested set pattern for ActiveRecord models. It is replacement for acts_as_nested_set and BetterNestedSet, but awesomer.
Chris@909: 
Chris@909: == What makes this so awesome?
Chris@909: 
Chris@909: This is a new implementation of nested set based off of BetterNestedSet that fixes some bugs, removes tons of duplication, adds a few useful methods, and adds STI support.
Chris@909: 
Chris@909: == Installation
Chris@909: 
Chris@909: If you are on Rails 2.1 or later:
Chris@909: 
Chris@909:   script/plugin install git://github.com/collectiveidea/awesome_nested_set.git
Chris@909:   
Chris@909: == Usage
Chris@909: 
Chris@909: To make use of awesome_nested_set, your model needs to have 3 fields: lft, rgt, and parent_id:
Chris@909: 
Chris@909:   class CreateCategories < ActiveRecord::Migration
Chris@909:     def self.up
Chris@909:       create_table :categories do |t|
Chris@909:         t.string :name
Chris@909:         t.integer :parent_id
Chris@909:         t.integer :lft
Chris@909:         t.integer :rgt
Chris@909:       end
Chris@909:     end
Chris@909: 
Chris@909:     def self.down
Chris@909:       drop_table :categories
Chris@909:     end
Chris@909:   end
Chris@909: 
Chris@909: Enable the nested set functionality by declaring acts_as_nested_set on your model
Chris@909: 
Chris@909:   class Category < ActiveRecord::Base
Chris@909:     acts_as_nested_set
Chris@909:   end
Chris@909:   
Chris@909: Run `rake rdoc` to generate the API docs and see CollectiveIdea::Acts::NestedSet::SingletonMethods for more info.
Chris@909: 
Chris@909: == View Helper
Chris@909: 
Chris@909: The view helper is called #nested_set_options. 
Chris@909: 
Chris@909: Example usage:
Chris@909: 
Chris@909:   <%= f.select :parent_id, nested_set_options(Category, @category) {|i| "#{'-' * i.level} #{i.name}" } %>
Chris@909: 
Chris@909:   <%= select_tag 'parent_id', options_for_select(nested_set_options(Category) {|i| "#{'-' * i.level} #{i.name}" } ) %>
Chris@909: 
Chris@909: See CollectiveIdea::Acts::NestedSet::Helper for more information about the helpers.
Chris@909: 
Chris@909: == References
Chris@909: 
Chris@909: You can learn more about nested sets at:
Chris@909: 
Chris@909:   http://www.dbmsmag.com/9603d06.html
Chris@909:   http://threebit.net/tutorials/nestedset/tutorial1.html
Chris@909:   http://api.rubyonrails.com/classes/ActiveRecord/Acts/NestedSet/ClassMethods.html
Chris@909:   http://opensource.symetrie.com/trac/better_nested_set/
Chris@909: 
Chris@909: 
Chris@909: Copyright (c) 2008 Collective Idea, released under the MIT license