require 'active_support/concern' require 'active_support/core_ext/class/attribute' module ActiveRecord module ReadonlyAttributes extend ActiveSupport::Concern included do class_attribute :_attr_readonly, :instance_writer => false self._attr_readonly = [] end module ClassMethods # Attributes listed as readonly will be used to create a new record but update operations will # ignore these fields. def attr_readonly(*attributes) self._attr_readonly = Set.new(attributes.map { |a| a.to_s }) + (self._attr_readonly || []) end # Returns an array of all the attributes that have been specified as readonly. def readonly_attributes self._attr_readonly end end end end