Merge branch 'hash' of https://github.com/edtsech/paper_trail into edtsech-hash

* 'hash' of https://github.com/edtsech/paper_trail:
  Changeset method return {} (empty hash) for create and destroy actions if object_changes column defined but return nil if column does not exist

README.md

@@ -458,7 +458,7 @@ There are two scenarios: diffing adjacent versions and diffing non-adjacent vers
 The best way to diff adjacent versions is to get PaperTrail to do it for you.  If you add an `object_changes` text column to your `versions` table, either at installation time with the `--with-changes` option or manually, PaperTrail will store the `changes` diff (excluding any attributes PaperTrail is ignoring) in each `update` version.  You can use the `version.changeset` method to retrieve it.  For example:
 
     >> widget = Widget.create :name => 'Bob'
-    >> widget.versions.last.changeset                # nil
+    >> widget.versions.last.changeset                # {}
     >> widget.update_attributes :name => 'Robert'
     >> widget.versions.last.changeset                # {'name' => ['Bob', 'Robert']}
 

lib/paper_trail/version.rb

@@ -81,7 +81,13 @@ class Version < ActiveRecord::Base
 
   # Returns what changed in this version of the item.  Cf. `ActiveModel::Dirty#changes`.
   def changeset
-    YAML::load(object_changes) if Version.method_defined?(:object_changes) && object_changes
+    if Version.method_defined?(:object_changes)
+      if changes = object_changes
+        YAML::load(changes)
+      else
+        {}
+      end
+    end
   end
 
   # Returns who put the item into the state stored in this version.

test/unit/model_test.rb

@@ -65,7 +65,7 @@ class HasPaperTrailModelTest < ActiveSupport::TestCase
       end
 
       should 'should not have changes' do
-        assert_nil @widget.versions.last.changeset
+        assert_equal Hash.new, @widget.versions.last.changeset
       end
 
       context 'and then updated without any changes' do