Ruby module to help create classes for form parameters (or other things). Also see Class2: https://github.com/sshaw/class2

form_fields.rb

module FormFields
  def self.included(klass)
    klass.class_eval do
      def self.fields(*args)
        args.flatten!
        attr_accessor(*args)
        @@fields = args.map(&:to_sym)
      end
    end
  end

  def initialize(hash = nil)
    (hash || {}).each do |name, value|
      next unless @@fields.include?(name) || name.respond_to?(:to_sym) && @@fields.include?(name.to_sym)
      public_send("#{name}=", value)
    end
  end

  def to_h
    @@fields.each_with_object({}) { |name, h| h[name] = public_send(name) }
  end
end

class SomeForm
  include FormFields
  include ActiveModel::Validations

  fields :foo, :bar, :baz

  validates :foo, :presence => true
end