I18n in models

class Person < ActiveRecord::Base

  # If I18n.t is evaluated when the model is loaded, which in production happens only once
  # the translation will always use the locale which was set at that moment.
  #
  # (Instead just use the activerecord.errors.person.attributes.email.invalid key in
  # the translation files)
  #
  # This does NOT work properly:
  validates_format_of :email, :with => REGEXP, :message => I18n.t(:email_invalid) 

  # Methods are evaluated on run time, so I18n.t works fine here:
  def validate
    errors.add(:email, I18n.t(:email_invalid)) unless email =~ REGEXP
  end

end