awesome_nested_set

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= AwesomeNestedSet

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.

== What makes this so awesome?

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.

== Installation

The plugin is available as a gem:

gem 'be9-awesome_nested_set'

Or install as a plugin:

rails plugin install git://github.com/be9/awesome_nested_set.git

== Usage

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.

== Conversion from other trees

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!

== View Helper

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.

== References

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/

== How to contribute

If you find what you might think is a bug:

1. Check the GitHub issue tracker to see if anyone else has had the same issue. http://github.com/collectiveidea/awesome_nested_set/issues/
2. 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:

1. Fork the project on github. http://github.com/collectiveidea/awesome_nested_set/
2. Make your changes with tests.
3. Commit the changes without making changes to the Rakefile, VERSION, or any other files that aren't related to your enhancement or fix
4. Send a pull request.

Copyright ©2010 Collective Idea, released under the MIT license