101 lines
3.0 KiB
Plaintext
101 lines
3.0 KiB
Plaintext
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= AwesomeNestedSet
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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.
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Version 2 supports Rails 3. Gem versions prior to 2.0 support Rails 2.
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== What makes this so awesome?
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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.
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== Installation
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Add to your Gemfile:
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gem 'awesome_nested_set'
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== Usage
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To make use of awesome_nested_set, your model needs to have 3 fields: lft, rgt, and parent_id:
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class CreateCategories < ActiveRecord::Migration
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def self.up
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create_table :categories do |t|
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t.string :name
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t.integer :parent_id
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t.integer :lft
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t.integer :rgt
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end
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end
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def self.down
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drop_table :categories
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end
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end
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Enable the nested set functionality by declaring acts_as_nested_set on your model
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class Category < ActiveRecord::Base
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acts_as_nested_set
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end
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Run `rake rdoc` to generate the API docs and see CollectiveIdea::Acts::NestedSet for more info.
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== Protecting attributes from mass assignment
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It's generally best to "white list" the attributes that can be used in mass assignment:
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class Category < ActiveRecord::Base
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acts_as_nested_set
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attr_accessible :name, :parent_id
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end
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If for some reason that is not possible, you will probably want to protect the lft and rgt attributes:
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class Category < ActiveRecord::Base
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acts_as_nested_set
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attr_protected :lft, :rgt
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end
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== Conversion from other trees
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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
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Category.rebuild!
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Your tree will be converted to a valid nested set. Awesome!
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== View Helper
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The view helper is called #nested_set_options.
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Example usage:
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<%= f.select :parent_id, nested_set_options(Category, @category) {|i| "#{'-' * i.level} #{i.name}" } %>
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<%= select_tag 'parent_id', options_for_select(nested_set_options(Category) {|i| "#{'-' * i.level} #{i.name}" } ) %>
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See CollectiveIdea::Acts::NestedSet::Helper for more information about the helpers.
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== References
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You can learn more about nested sets at: http://threebit.net/tutorials/nestedset/tutorial1.html
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== How to contribute
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If you find what you might think is a bug:
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1. Check the GitHub issue tracker to see if anyone else has had the same issue.
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http://github.com/collectiveidea/awesome_nested_set/issues/
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2. If you don't see anything, create an issue with information on how to reproduce it.
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If you want to contribute an enhancement or a fix:
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1. Fork the project on github.
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http://github.com/collectiveidea/awesome_nested_set/
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2. Make your changes with tests.
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3. 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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4. Send a pull request.
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Copyright ©2008 Collective Idea, released under the MIT license
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