From 941114ae34e01d3688f840d9497017ee91e7e21f Mon Sep 17 00:00:00 2001
From: James Prior <james@mabonus.net>
Date: Wed, 13 Apr 2011 22:17:25 -0500
Subject: [PATCH] Updating Dirty to no longer mark STI classes as changed when instantiated

---
 activerecord/lib/active_record/dirty.rb |   18 +++++++++++++-----
 activerecord/test/cases/dirty_test.rb   |   16 ++++++++++++++++
 2 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/activerecord/lib/active_record/dirty.rb b/activerecord/lib/active_record/dirty.rb
index 1db8fef..d8f2ed5 100644
--- a/activerecord/lib/active_record/dirty.rb
+++ b/activerecord/lib/active_record/dirty.rb
@@ -38,11 +38,12 @@ module ActiveRecord
 
     def self.included(base)
       base.attribute_method_suffix *DIRTY_SUFFIXES
-      base.alias_method_chain :write_attribute, :dirty
-      base.alias_method_chain :save,            :dirty
-      base.alias_method_chain :save!,           :dirty
-      base.alias_method_chain :update,          :dirty
-      base.alias_method_chain :reload,          :dirty
+      base.alias_method_chain :write_attribute,     :dirty
+      base.alias_method_chain :save,                :dirty
+      base.alias_method_chain :save!,               :dirty
+      base.alias_method_chain :update,              :dirty
+      base.alias_method_chain :reload,              :dirty
+      base.alias_method_chain :ensure_proper_type,  :dirty
 
       base.class_attribute :partial_updates
       base.partial_updates = true
@@ -95,6 +96,13 @@ module ActiveRecord
       changed_attributes.clear
       record
     end
+    
+    # sets the inheritance column and clears changed attributes
+    def ensure_proper_type_with_dirty(*args) #:nodoc:
+      result = ensure_proper_type_without_dirty(*args)
+      changed_attributes.clear
+      result
+    end
 
     private
       # Map of change <tt>attr => original value</tt>.
diff --git a/activerecord/test/cases/dirty_test.rb b/activerecord/test/cases/dirty_test.rb
index fb3d26f..4e2bf21 100644
--- a/activerecord/test/cases/dirty_test.rb
+++ b/activerecord/test/cases/dirty_test.rb
@@ -148,6 +148,22 @@ class DirtyTest < ActiveRecord::TestCase
     assert_equal [], pirate.changed
     assert_equal Hash.new, pirate.changes
   end
+  
+  def test_inherited_object_should_not_be_changed_when_instantiated
+    # Using an STI class here
+    live_parrot = LiveParrot.new
+    assert !live_parrot.changed?
+    
+    live_parrot.name = 'Susan'
+    live_parrot.save!
+    
+    assert !live_parrot.changed?
+    assert_equal [], live_parrot.changed
+    assert_equal Hash.new, live_parrot.changes
+    
+    live_parrot = LiveParrot.find_by_name('Susan')
+    assert !live_parrot.changed?
+  end
 
   def test_attribute_will_change!
     pirate = Pirate.create!(:catchphrase => 'arr')
-- 
1.6.0.2