Specify this act if you want to model a tree structure by providing a parent association and a children association. This act 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 \_ subchild1 \_ subchild2 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
In addition to the parent and children associations, the following instance methods are added to the class after specifying the act:
- siblings : Returns all the children of the parent, excluding the current node ([ subchild2 ] when called from subchild1)
- self_and_siblings : Returns all the children of the parent, including the current node ([ subchild1, subchild2 ] when called from subchild1)
- ancestors : Returns all the ancestors of the current node ([child1, root] when called from subchild2)
- root : Returns the root of the current node (root when called from subchild2)