validation_reflection_remember_data.rb

# lib/validation_reflection.rb
def remember_validation_metadata(validation_type, *attr_names)
  configuration = attr_names.last.is_a?(::Hash) ? attr_names.pop : {}
  attr_names.flatten.each do |attr_name|
    self.write_inheritable_array :validations,
      [::ActiveRecord::Reflection::MacroReflection.new(validation_type, attr_name.to_sym, configuration, self)]
  end
end