Added ActiveRecord::Mixins::Touch that will record creation and update times of objects [xal]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@85 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/CHANGELOG

@@ -1,5 +1,19 @@
 *CVS*
 
+* Added ActiveRecord::Mixins::Touch that will record creation and update times of objects [xal]. Example:
+
+    class Bill < ActiveRecord::Base
+      include ActiveRecord::Mixins::Touch
+    end
+  
+    bill = Bill.create("amount" => 100)
+    bill.created_at # => Time.now at the moment of Bill.create
+    bill.updated_at # => Time.now at the moment of Bill.create
+  
+    bill.update_attribute("amount", 150)
+    bill.created_at # => Time.now at the moment of Bill.create
+    bill.updated_at # => Time.now at the moment of bill.update_attribute
+  
 * Added ActiveRecord::Mixins::List that can decorates an existing class with methods like move_higher/lower, move_to_top/bottom. Example:
 
     class TodoItem < ActiveRecord::Base
@@ -11,7 +25,7 @@
           "todo_list_id = #{todo_list_id}"
         end
     end
-  
+
 * Added the option for sanitizing find_by_sql and the offset parts in regular finds [Sam Stephenson]. Examples:
 
     Project.find_all ["category = ?", category_name], "created ASC", ["? OFFSET ?", 15, 20]

activerecord/lib/active_record/mixins/touch.rb

@@ -0,0 +1,35 @@
+module ActiveRecord
+  module Mixins
+    # Including this mixins will record when objects of the class are created in a datetime column called "created_at"
+    # and when its updated in another datetime column called "updated_at".
+    #
+    #   class Bill < ActiveRecord::Base
+    #     include ActiveRecord::Mixins::Touch
+    #   end
+    #
+    #   bill = Bill.create("amount" => 100)
+    #   bill.created_at # => Time.now at the moment of Bill.create
+    #   bill.updated_at # => Time.now at the moment of Bill.create
+    #
+    #   bill.update_attribute("amount", 150)
+    #   bill.created_at # => Time.now at the moment of Bill.create
+    #   bill.updated_at # => Time.now at the moment of bill.update_attribute
+    module Touch
+      def self.append_features(base)
+        super
+        base.class_eval do
+          before_create :touch_on_create
+          before_update :touch_on_update
+
+          def touch_on_create
+            self.created_at = self.updated_at = Time.now
+          end
+
+          def touch_on_update
+            self.updated_at = Time.now
+          end
+        end
+      end  
+    end
+  end
+end