global

For more: https://github.com/rails-api/active_model_serializers/issues/127

do this. Feel free to remove this if you don't feel that it's appropriate.
#object_id, we recommend that if you wish to serialize id columns, you
due to the difference between 1.8 and 1.9 with respect to #id and

def id
  object.read_attribute_for_serialization(:id)
end