Module | ActiveRecord::Acts::Tree::ClassMethods |
In: |
vendor/rails/activerecord/lib/active_record/acts/tree.rb
|
Specify this act if you want to model a tree structure by providing a parent association and an children association. This act assumes that requires that you have a foreign key column, which by default is called parent_id.
class Category < ActiveRecord::Base acts_as_tree :order => "name" end Example : root \_ child1 \_ sub-child1 root = Category.create("name" => "root") child1 = root.children.create("name" => "child1") subchild1 = child1.children.create("name" => "subchild1") root.parent # => nil child1.parent # => root root.children # => [child1] root.children.first.children.first # => subchild1
Configuration options are:
# File vendor/rails/activerecord/lib/active_record/acts/tree.rb, line 35 35: def acts_as_tree(options = {}) 36: configuration = { :foreign_key => "parent_id", :order => nil, :counter_cache => nil } 37: configuration.update(options) if options.is_a?(Hash) 38: 39: belongs_to :parent, :class_name => name, :foreign_key => configuration[:foreign_key], :counter_cache => configuration[:counter_cache] 40: has_many :children, :class_name => name, :foreign_key => configuration[:foreign_key], :order => configuration[:order], :dependent => true 41: 42: module_eval "def self.roots\nself.find(:all, :conditions => \"\#{configuration[:foreign_key]} IS NULL\", :order => \"\#{configuration[:order]}\")\nend\ndef self.root\nself.find(:first, :conditions => \"\#{configuration[:foreign_key]} IS NULL\", :order => \"\#{configuration[:order]}\")\nend\n" 43: 44: define_method(:siblings) do 45: if parent 46: self.class.find(:all, :conditions => [ "#{configuration[:foreign_key]} = ?", parent.id ], :order => configuration[:order]) 47: else 48: self.class.roots 49: end 50: end 51: end