class ActiveModel::Serializer

def relationship_value_for(association, adapter_options, adapter_instance)
  return association.options[:virtual_value] if association.options[:virtual_value]
  association_serializer = association.serializer
  association_object = association_serializer && association_serializer.object
  return unless association_object
  relationship_value = association_serializer.serializable_hash(adapter_options, {}, adapter_instance)
  if association.options[:polymorphic] && relationship_value
    polymorphic_type = association_object.class.name.underscore
    relationship_value = { type: polymorphic_type, polymorphic_type.to_sym => relationship_value }
  end
  relationship_value
end