Rails I18n fallback locales

When you need to create a locale for a language variant (like Austrian for German), you probably don't want to duplicate your entire de.yml file only to change a few minor exceptions for our Austrian friends.

Luckily, the I18n gem used by Rails has a fallback feature Show archive.org snapshot where you can make one locale file fall back to another if no translation is available.

In the example above you would have a config/locales/de_DE.yml:

de_DE:
  # hundreds of translations here

... and another locale config/locales/de_AT.yml:

de_AT:
  # only a handful exceptions here

Now configure Rails Show archive.org snapshot to make de_AT fall back to de_DE:

Rails.application.configure do
  config.i18n.fallbacks = { de_AT: :de_DE }
end

Check if a key is defined in the current locale (without fallback)

Do this:

I18n.exists?('my.key', fallback: false)

Rails 2

For Rails 2.3.11 you need to upgrade your project to use the I18n gem by adding this to the top of your Gemfile:

gem 'i18n'

Then run

bundle install