circular bug fix, see: #211

Author: Colby Swandale

lib/active_model/serializer/associations.rb

@@ -93,7 +93,19 @@ def find_serializable(object)
           if target_serializer
             target_serializer.new(object, source_serializer.options)
           elsif object.respond_to?(:active_model_serializer) && (ams = object.active_model_serializer)
-            ams.new(object, source_serializer.options)
+            source_association = source_serializer.object.class.to_s.underscore.downcase
+            plural_source_association = source_association+'s'
+            except = ams._associations.keys.map(&:to_s).find do |association|
+              association == source_association || association == plural_source_association
+            end
+            _options = source_serializer.options
+            _options[:except] = Array(_options[:except])
+            if not except.nil?
+              if not _options[:except].include? except.to_sym
+                _options[:except].push(except.to_sym)
+              end
+            end
+            ams.new(object, _options)
           else
             object
           end