When building the :object_changes metadata, use the serialized value for any attributes that are serialized

lib/paper_trail/has_paper_trail.rb

@@ -175,15 +175,29 @@ module PaperTrail
             :whodunnit => PaperTrail.whodunnit
           }
           if version_class.column_names.include? 'object_changes'
-            # The double negative (reject, !include?) preserves the hash structure of self.changes.
-            data[:object_changes] = self.changes.reject do |key, value|
-              !notably_changed.include?(key)
-            end.to_yaml
+            data[:object_changes] = changes_for_paper_trail.to_yaml
           end
           send(self.class.versions_association_name).build merge_metadata(data)
         end
       end
 
+      def changes_for_paper_trail
+        # The double negative (reject, !include?) preserves the hash structure of self.changes.
+        self.changes.reject do |key, value|
+          !notably_changed.include?(key)
+        end.tap do |changes_hash|
+          # Use serialized value for attributes that are serialized
+          changes_hash.each do |key, (old_value, new_value)|
+            if serialized_attributes.include?(key)
+              # serializer.dump(new_value) is the same as @attributes[key].serialized_value
+              serializer = @attributes[key].coder
+              changes_hash[key] = [serializer.dump(old_value),
+                                   serializer.dump(new_value)]
+            end
+          end
+        end
+      end
+
       def record_destroy
         if switched_on? and not new_record?
           version_class.create merge_metadata(:item_id   => self.id,

test/dummy/app/models/person.rb

@@ -2,4 +2,27 @@ class Person < ActiveRecord::Base
   has_many :authorships, :dependent => :destroy
   has_many :books, :through => :authorships
   has_paper_trail
+
+  # Convert strings to TimeZone objects when assigned
+  def time_zone=(value)
+    if value.is_a? ActiveSupport::TimeZone
+      super
+    else
+      zone = ::Time.find_zone(value)  # nil if can't find time zone
+      super zone
+    end
+  end
+
+  # Store TimeZone objects as strings when serialized to database
+  class TimeZoneSerializer
+    def dump(zone)
+      zone.try(:name)
+    end
+   
+    def load(value)
+      ::Time.find_zone!(value) rescue nil
+    end
+  end
+ 
+  serialize :time_zone, TimeZoneSerializer.new
 end

test/dummy/db/migrate/20110208155312_set_up_test_tables.rb

@@ -80,6 +80,7 @@ class SetUpTestTables < ActiveRecord::Migration
 
     create_table :people, :force => true do |t|
       t.string :name
+      t.string "time_zone"
     end
 
     create_table :songs, :force => true do |t|

test/unit/model_test.rb

@@ -906,6 +906,29 @@ class HasPaperTrailModelTest < ActiveSupport::TestCase
     end
   end
 
+  context 'When an attribute has a custom serializer' do
+    setup { @person = Person.create(:time_zone => "UTC") }
+
+    should "be an instance of ActiveSupport::TimeZone" do
+      assert_equal ActiveSupport::TimeZone, @person.time_zone.class
+    end
+
+    context 'when that attribute is updated' do
+      setup { @person.update_attributes({ :time_zone => 'Pacific Time (US & Canada)' }) }
+
+      should 'have used the value returned by the serializer' do
+        assert_equal ['UTC', 'Pacific Time (US & Canada)'], @person.versions.last.changeset[:time_zone]
+        assert_equal @person.instance_variable_get(:@attributes)['time_zone'].serialized_value, @person.versions.last.changeset[:time_zone].last
+      end
+
+      should 'not have stored the default, ridiculously long (to_yaml) serialization of the time_zone object' do
+        # Before the serialized attributes fix, the object_changes that was stored was ridiculously long (58723)
+        assert @person.versions.last.object_changes.length < 105, "object_changes length was #{@person.versions.last.object_changes.length}"
+      end
+    end
+  end
+
+
   context 'A new model instance which uses a custom Version class' do
     setup { @post = Post.new }