form_model.rb

class FormModel

  extend ActiveModel::Naming
  include ActiveModel::Conversion
  include ActiveModel::Validations

  def self.form_fields
    @form_fields ||= []
  end

  def self.form_fields=(form_fields)
    @form_fields = form_fields
  end

  def self.add_form_field(*form_fields)
    form_fields = form_fields.flatten.compact
    self.form_fields = form_fields

    form_fields.each do |field|
      delegate :"#{field}", to: :protected_model
      delegate :"#{field}=", to: :protected_model
    end
  end

  def self.add_readonly_form_fields(*form_fields)
    form_fields = form_fields.flatten.compact

    form_fields.each do |field|
      delegate :"#{field}", to: :protected_model
    end
  end

  attr_accessor :protected_model

  def errors
    protected_model.errors
  end

  def persisted?
    protected_model.persisted?
  end

  def save
    protected_model.update_attributes(attributes)

    if valid? && protected_model.valid?
      protected_model.save
    else
      false
    end
  end

  def id
    protected_model.id
  end

end