Merge pull request #377 from cfinucane/fix/has_one_autosave

extend approach from #344 to fix autosave for has_one associations as well

lib/composite_primary_keys/autosave_association.rb

@@ -27,5 +27,39 @@ def save_belongs_to_association(reflection)
           end
         end
       end
+
+      # Saves the associated record if it's new or <tt>:autosave</tt> is enabled
+      # on the association.
+      #
+      # In addition, it will destroy the association if it was marked for
+      # destruction with mark_for_destruction.
+      #
+      # This all happens inside a transaction, _if_ the Transactions module is included into
+      # ActiveRecord::Base after the AutosaveAssociation module, which it does by default.
+      def save_has_one_association(reflection)
+        association = association_instance_get(reflection.name)
+        record      = association && association.load_target
+
+        if record && !record.destroyed?
+          autosave = reflection.options[:autosave]
+
+          if autosave && record.marked_for_destruction?
+            record.destroy
+          elsif autosave != false
+            # it will fail to use "#send(reflection.options[:primary_key])" for CPK
+            key = reflection.options[:primary_key] ? record.read_attribute(reflection.options[:primary_key]) : id
+
+            if (autosave && record.changed_for_autosave?) || new_record? || record_changed?(reflection, record, key)
+              unless reflection.through_reflection
+                record[reflection.foreign_key] = key
+              end
+
+              saved = record.save(:validate => !autosave)
+              raise ActiveRecord::Rollback if !saved && autosave
+              saved
+            end
+          end
+        end
+      end
   end
 end