Spanish postal code validator for Rails

spanish_postal_code_validator.rb

# Usage:
#
# class MyClass < ActiveRecord::Base
#   ...
#   validate :postal_code, spanish_postal_code: true # default message
#   validate :postal_code, spanish_postal_code: { message: '<Your message>' } # custom message
#   ...
# end
#
class SpanishPostalCodeValidator < ActiveModel::EachValidator
  def validate_each(object, attribute, value)
    unless value =~ /\A(0[1-9]|[1-4][0-9]|5[0-2])\d{3}\z/i
      object.errors[attribute] << options.fetch(:message, I18n.t('errors.messages.invalid'))
    end
  end
end