Add moderated_fields_for method

lib/the_moderator/model.rb

@@ -23,6 +23,11 @@ module TheModerator
       false
     end
 
+    def moderated_fields_for(assoc)
+      moderations.map { |m| m.moderated_fields_for(assoc) }
+                 .inject(&:|)
+    end
+
     protected
 
     def moderation_data(*moderated_attributes)

lib/the_moderator/moderation_model.rb

@@ -41,6 +41,10 @@ module TheModerator
       include_attribute?(attribute, data[:attributes])
     end
 
+    def moderated_fields_for(assoc)
+      (data[:attributes][assoc].try(:keys) || []) - [:id]
+    end
+
     private
 
     def include_attribute?(attribute, attr_data)