Question

I am using Ruby on Rails 3.1.0 and the I18n gem. I (am implementing a plugin and) I would like to check at runtime if the I18n is missing a translation key/value pairs and, if so, to use a custom string. That is, I have:

validates :link_url,
  :format     => {
    :with => REGEX,
    :message  => I18n.t(
      'custom_invalid_format',
      :scope => 'activerecord.errors.messages'
  )
}

If in the .yml file there is not the following code

activerecord:
  errors:
    messages:
      custom_invalid_format: This is the test error message 1

I would like to use the This is the test error message 2. Is it possible? If so, how can I make that?

BTW: For performance reasons, is it advisable to check at runtime if the translation key/value pairs is present?

Answer 1

I just had the same question and I want to compute an automatic string in case the translation is missing. If I use the :default option I have to compute the automatic string every time even when the translation is not missing. So I searched for another solution.

You can add the option :raise => true or use I18n.translate! instead of I18n.translate. If no translation can be found an exception is raised.

begin
  I18n.translate!('this.key.should.be.translated', :raise => true) 
rescue I18n::MissingTranslationData
  do_some_resource_eating_text_generation_here
end