From 6860db61f516b813af624d38b47fef0bf983539c Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Thu, 16 Dec 2004 16:23:59 +0000
Subject: Renamed Mixins to Acts to resemble the change from include
 ActiveRecord::Mixins::List to acts_as_list and renamed
 @@default_error_messagess to @@default_error_messages

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@190 5ecf4fe2-1ee6-0310-87b1-e25e094e27de
---
 activerecord/lib/active_record/acts/tree.rb | 40 +++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 activerecord/lib/active_record/acts/tree.rb

(limited to 'activerecord/lib/active_record/acts/tree.rb')

diff --git a/activerecord/lib/active_record/acts/tree.rb b/activerecord/lib/active_record/acts/tree.rb
new file mode 100644
index 0000000000..f05bbe9a78
--- /dev/null
+++ b/activerecord/lib/active_record/acts/tree.rb
@@ -0,0 +1,40 @@
+module ActiveRecord
+  module Acts
+    # Including this mixin if you want to model a tree structure by providing a parent association and an children 
+    # association. This mixin assumes that you have a column called parent_id
+    # 
+    #   class Category < ActiveRecord::Base
+    #     include ActiveRecord::Mixins::Tree
+    #   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
+    module Tree
+      def self.append_features(base)
+        super        
+        base.extend(ClassMethods)              
+      end  
+    end
+    
+    module ClassMethods
+      def acts_as_tree(options = {})
+        configuration = { :foreign_key => "parent_id", :order => nil }
+        configuration.update(options) if options.is_a?(Hash)
+        
+        belongs_to :parent, :class_name => name, :foreign_key => configuration[:foreign_key]
+        has_many :children, :class_name => name, :foreign_key => configuration[:foreign_key], :order => configuration[:order], :dependent => true
+      end
+    end
+  end
+end
\ No newline at end of file
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