Chris@1115: = AwesomeNestedSet
Chris@1115: 
Chris@1115: 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 more awesome.
Chris@1115: 
Chris@1115: Version 2 supports Rails 3. Gem versions prior to 2.0 support Rails 2.
Chris@1115: 
Chris@1115: == What makes this so awesome?
Chris@1115: 
Chris@1115: 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@1115: 
Chris@1115: == Installation
Chris@1115: 
Chris@1115:   Add to your Gemfile:
Chris@1115: 
Chris@1115:   gem 'awesome_nested_set'
Chris@1115: 
Chris@1115: == Usage
Chris@1115: 
Chris@1115: To make use of awesome_nested_set, your model needs to have 3 fields: lft, rgt, and parent_id:
Chris@1115: 
Chris@1115:   class CreateCategories < ActiveRecord::Migration
Chris@1115:     def self.up
Chris@1115:       create_table :categories do |t|
Chris@1115:         t.string :name
Chris@1115:         t.integer :parent_id
Chris@1115:         t.integer :lft
Chris@1115:         t.integer :rgt
Chris@1115:       end
Chris@1115:     end
Chris@1115: 
Chris@1115:     def self.down
Chris@1115:       drop_table :categories
Chris@1115:     end
Chris@1115:   end
Chris@1115: 
Chris@1115: Enable the nested set functionality by declaring acts_as_nested_set on your model
Chris@1115: 
Chris@1115:   class Category < ActiveRecord::Base
Chris@1115:     acts_as_nested_set
Chris@1115:   end
Chris@1115: 
Chris@1115: Run `rake rdoc` to generate the API docs and see CollectiveIdea::Acts::NestedSet for more info.
Chris@1115: 
Chris@1115: == Protecting attributes from mass assignment
Chris@1115: 
Chris@1115: It's generally best to "white list" the attributes that can be used in mass assignment:
Chris@1115: 
Chris@1115:   class Category < ActiveRecord::Base
Chris@1115:     acts_as_nested_set
Chris@1115:     attr_accessible :name, :parent_id
Chris@1115:   end
Chris@1115: 
Chris@1115: If for some reason that is not possible, you will probably want to protect the lft and rgt attributes:
Chris@1115: 
Chris@1115:   class Category < ActiveRecord::Base
Chris@1115:     acts_as_nested_set
Chris@1115:     attr_protected :lft, :rgt
Chris@1115:   end
Chris@1115: 
Chris@1115: == Conversion from other trees
Chris@1115: 
Chris@1115: Coming from acts_as_tree or another system where you only have a parent_id? No problem. Simply add the lft & rgt fields as above, and then run
Chris@1115: 
Chris@1115:   Category.rebuild!
Chris@1115: 
Chris@1115: Your tree will be converted to a valid nested set. Awesome!
Chris@1115: 
Chris@1115: == View Helper
Chris@1115: 
Chris@1115: The view helper is called #nested_set_options.
Chris@1115: 
Chris@1115: Example usage:
Chris@1115: 
Chris@1115:   <%= f.select :parent_id, nested_set_options(Category, @category) {|i| "#{'-' * i.level} #{i.name}" } %>
Chris@1115: 
Chris@1115:   <%= select_tag 'parent_id', options_for_select(nested_set_options(Category) {|i| "#{'-' * i.level} #{i.name}" } ) %>
Chris@1115: 
Chris@1115: See CollectiveIdea::Acts::NestedSet::Helper for more information about the helpers.
Chris@1115: 
Chris@1115: == References
Chris@1115: 
Chris@1115: You can learn more about nested sets at: http://threebit.net/tutorials/nestedset/tutorial1.html
Chris@1115: 
Chris@1115: == How to contribute
Chris@1115: 
Chris@1115: If you find what you might think is a bug:
Chris@1115: 
Chris@1115: 1. Check the GitHub issue tracker to see if anyone else has had the same issue.
Chris@1115:    http://github.com/collectiveidea/awesome_nested_set/issues/
Chris@1115: 2. If you don't see anything, create an issue with information on how to reproduce it.
Chris@1115: 
Chris@1115: If you want to contribute an enhancement or a fix:
Chris@1115: 
Chris@1115: 1. Fork the project on github.
Chris@1115:    http://github.com/collectiveidea/awesome_nested_set/
Chris@1115: 2. Make your changes with tests.
Chris@1115: 3. Commit the changes without making changes to the Rakefile, VERSION, or any other files that aren't related to your enhancement or fix
Chris@1115: 4. Send a pull request.
Chris@1115: 
Chris@1115: Copyright ©2008 Collective Idea, released under the MIT license