force datetime attributes to be changed

backport ddb5d2f756d9d2655a07791a3b62832efd588474 to 3-2-stable

2 files changed, 15 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb b/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb
index 17cf34cdf6..c9b2edbd8c 100644
--- a/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb
+++ b/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb
@@ -43,6 +43,7 @@ module ActiveRecord
                   end
                   time = time.in_time_zone rescue nil if time
                   write_attribute(:#{attr_name}, original_time)
+                  #{attr_name}_will_change!
                   @attributes_cache["#{attr_name}"] = time
                 end
               EOV
diff --git a/activerecord/test/cases/attribute_methods_test.rb b/activerecord/test/cases/attribute_methods_test.rb
index acb9a44305..5e5325b570 100644
--- a/activerecord/test/cases/attribute_methods_test.rb
+++ b/activerecord/test/cases/attribute_methods_test.rb
@@ -620,6 +620,20 @@ class AttributeMethodsTest < ActiveRecord::TestCase
     end
   end
 
+  def test_time_zone_aware_attribute_saved
+    old_default, ActiveRecord::Base.default_timezone = ActiveRecord::Base.default_timezone, :utc
+
+    in_time_zone 1 do
+      record = @target.create(:written_on => '2012-02-20 10:00')
+
+      record.written_on = '2012-02-20 09:00'
+      record.save
+      assert_equal Time.zone.local(2012, 02, 20, 9), record.reload.written_on
+    end
+  ensure
+    ActiveRecord::Base.default_timezone = old_default
+  end
+
   def test_setting_time_zone_aware_attribute_to_blank_string_returns_nil
     in_time_zone "Pacific Time (US & Canada)" do
       record   = @target.new