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. It supports Rails 3.0.rc and later.
See, it’s Rails 3 only.
Sun Feb 20 17:52:28 EST 2011
Updated active record dependency to 3.0.0 to enable newer versions of Rails
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.
The plugin is available as a gem:
gem 'gwright-awesome_nested_set'
Or install as a plugin:
rails plugin install git://github.com/gwright/awesome_nested_set.git
To make use of awesome_nested_set, your model needs to have 3 fields: lft, rgt, and parent_id:
class CreateCategories < ActiveRecord::Migration def self.up create_table :categories do |t| t.string :name t.integer :parent_id t.integer :lft t.integer :rgt # Uncomment it to store item level # t.integer :depth end end def self.down drop_table :categories end end
Enable the nested set functionality by declaring acts_as_nested_set on your model
class Category < ActiveRecord::Base acts_as_nested_set end
Run ‘rake rdoc` to generate the API docs and see CollectiveIdea::Acts::NestedSet::Base::SingletonMethods for more info.
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
Category.rebuild!
Your tree be converted to a valid nested set. Awesome!
The view helper is called #nested_set_options.
Example usage:
<%= f.select :parent_id, nested_set_options(Category, @category) {|i| "#{'-' * i.level} #{i.name}" } %> <%= select_tag 'parent_id', options_for_select(nested_set_options(Category) {|i| "#{'-' * i.level} #{i.name}" } ) %>
See CollectiveIdea::Acts::NestedSet::Helper for more information about the helpers.
You can learn more about nested sets at:
http://www.dbmsmag.com/9603d06.html http://threebit.net/tutorials/nestedset/tutorial1.html http://api.rubyonrails.com/classes/ActiveRecord/Acts/NestedSet/ClassMethods.html http://opensource.symetrie.com/trac/better_nested_set/
If you find what you might think is a bug:
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Check the GitHub issue tracker to see if anyone else has had the same issue. github.com/collectiveidea/awesome_nested_set/issues/
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If you don’t see anything, create an issue with information on how to reproduce it.
If you want to contribute an enhancement or a fix:
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Fork the project on github. github.com/collectiveidea/awesome_nested_set/
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Make your changes with tests.
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Commit the changes without making changes to the Rakefile, VERSION, or any other files that aren’t related to your enhancement or fix
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Send a pull request.
Copyright ©2010 Collective Idea, released under the MIT license