module ActiveModelSerializers::Model::DeriveAttributesFromNamesAndFixAccessors

def self.included(base) 

def self.included(base)
  # NOTE that +id+ will always be in +attributes+.
  base.attributes :id
end

def attributes

the actual values in the model.
+attributes+ are returned frozen to prevent any expectations that mutation affects
The the fields in +attribute_names+ determines the returned hash.

Override the +attributes+ method so that the hash is derived from +attribute_names+. 
def attributes
  self.class.attribute_names.each_with_object({}) do |attribute_name, result|
    result[attribute_name] = public_send(attribute_name).freeze
  end.with_indifferent_access.freeze
end