Chris@909: module ActiveRecord Chris@909: module Acts Chris@909: module Tree Chris@909: def self.included(base) Chris@909: base.extend(ClassMethods) Chris@909: end Chris@909: Chris@909: # Specify this +acts_as+ extension if you want to model a tree structure by providing a parent association and a children Chris@909: # association. This requires that you have a foreign key column, which by default is called +parent_id+. Chris@909: # Chris@909: # class Category < ActiveRecord::Base Chris@909: # acts_as_tree :order => "name" Chris@909: # end Chris@909: # Chris@909: # Example: Chris@909: # root Chris@909: # \_ child1 Chris@909: # \_ subchild1 Chris@909: # \_ subchild2 Chris@909: # Chris@909: # root = Category.create("name" => "root") Chris@909: # child1 = root.children.create("name" => "child1") Chris@909: # subchild1 = child1.children.create("name" => "subchild1") Chris@909: # Chris@909: # root.parent # => nil Chris@909: # child1.parent # => root Chris@909: # root.children # => [child1] Chris@909: # root.children.first.children.first # => subchild1 Chris@909: # Chris@909: # In addition to the parent and children associations, the following instance methods are added to the class Chris@909: # after calling acts_as_tree: Chris@909: # * siblings - Returns all the children of the parent, excluding the current node ([subchild2] when called on subchild1) Chris@909: # * self_and_siblings - Returns all the children of the parent, including the current node ([subchild1, subchild2] when called on subchild1) Chris@909: # * ancestors - Returns all the ancestors of the current node ([child1, root] when called on subchild2) Chris@909: # * root - Returns the root of the current node (root when called on subchild2) Chris@909: module ClassMethods Chris@909: # Configuration options are: Chris@909: # Chris@909: # * foreign_key - specifies the column name to use for tracking of the tree (default: +parent_id+) Chris@909: # * order - makes it possible to sort the children according to this SQL snippet. Chris@909: # * counter_cache - keeps a count in a +children_count+ column if set to +true+ (default: +false+). Chris@909: def acts_as_tree(options = {}) Chris@909: configuration = { :foreign_key => "parent_id", :dependent => :destroy, :order => nil, :counter_cache => nil } Chris@909: configuration.update(options) if options.is_a?(Hash) Chris@909: Chris@909: belongs_to :parent, :class_name => name, :foreign_key => configuration[:foreign_key], :counter_cache => configuration[:counter_cache] Chris@909: has_many :children, :class_name => name, :foreign_key => configuration[:foreign_key], :order => configuration[:order], :dependent => configuration[:dependent] Chris@909: Chris@909: class_eval <<-EOV Chris@909: include ActiveRecord::Acts::Tree::InstanceMethods Chris@909: Chris@909: def self.roots Chris@909: find(:all, :conditions => "#{configuration[:foreign_key]} IS NULL", :order => #{configuration[:order].nil? ? "nil" : %Q{"#{configuration[:order]}"}}) Chris@909: end Chris@909: Chris@909: def self.root Chris@909: find(:first, :conditions => "#{configuration[:foreign_key]} IS NULL", :order => #{configuration[:order].nil? ? "nil" : %Q{"#{configuration[:order]}"}}) Chris@909: end Chris@909: EOV Chris@909: end Chris@909: end Chris@909: Chris@909: module InstanceMethods Chris@909: # Returns list of ancestors, starting from parent until root. Chris@909: # Chris@909: # subchild1.ancestors # => [child1, root] Chris@909: def ancestors Chris@909: node, nodes = self, [] Chris@909: nodes << node = node.parent while node.parent Chris@909: nodes Chris@909: end Chris@909: Chris@909: # Returns list of descendants. Chris@909: # Chris@909: # root.descendants # => [child1, subchild1, subchild2] Chris@909: def descendants Chris@909: children + children.collect(&:children).flatten Chris@909: end Chris@909: Chris@909: # Returns list of descendants and a reference to the current node. Chris@909: # Chris@909: # root.self_and_descendants # => [root, child1, subchild1, subchild2] Chris@909: def self_and_descendants Chris@909: [self] + descendants Chris@909: end Chris@909: Chris@909: # Returns the root node of the tree. Chris@909: def root Chris@909: node = self Chris@909: node = node.parent while node.parent Chris@909: node Chris@909: end Chris@909: Chris@909: # Returns all siblings of the current node. Chris@909: # Chris@909: # subchild1.siblings # => [subchild2] Chris@909: def siblings Chris@909: self_and_siblings - [self] Chris@909: end Chris@909: Chris@909: # Returns all siblings and a reference to the current node. Chris@909: # Chris@909: # subchild1.self_and_siblings # => [subchild1, subchild2] Chris@909: def self_and_siblings Chris@909: parent ? parent.children : self.class.roots Chris@909: end Chris@909: end Chris@909: end Chris@909: end Chris@909: end