How to configure locale aliases using i18n & rails?

Question

I am working on a rails app (3.2.13) that is being translated into several languages, including (one of the 3 available flavours of) Norwegian. On public pages, the app uses the browser's language settings to set locale.

Most browsers offer 3 separate Norwegian shortcodes: no, nb & nn. The translations we have are in nb, but I think it would be best if no & nn also defaulted to nb. That way, if a user's browser language preferences were set to no then en, the app would try to supply nb Norwegian first, instead of skipping straight to English.

Is it possible to configure a list of "language aliases" for the i18n gem, something like this?

 config.i18n.available_locales = [:sv, :en, :nb, :da, :fi]
 config.i18n.aliased_locales = [:nb <= :no, :nb <= :nn]

Answer 1

Short answer

Take a look to the fallbacks

Create a file in initializers like i18n_fallbacks.rb

config.i18n.fallbacks = {:no => [:nb], :nn => [:nb]}

Here the reference

Things related

You can even set multiple fallbacks, and they will be taken in the same order as specified:

for instance:

config.i18n.default_locale = :de
config.i18n.fallbacks = {:de => [:en,:es]}

de.yml

  :de:
    greeting: Hallo

en.yml

  :en:
    foo: bar

es.yml

  :es:
    bar: baz

You get the following:

I18n.t :greeting # found in de.yml, no fallback
# => 'Hallo'

I18n.t :foo # not in :de, try in :en and found
# => "bar"

I18n.t :bar # not in :de, try in :en and in :es
# => "baz"

I81n.t :other # not found anywhere, note the message delivers not found for the current locale:
# => "translation missing: de.other"

Answer 2

In latest i18n gem (0.7.0) I have found it necessary to define fallback locales like this (in config/application.rb):

# Custom I18n fallbacks
config.after_initialize do
  I18n.fallbacks = I18n::Locale::Fallbacks.new(at: :"de-DE", ch: :"de-DE", gb: :"en-US")
end

You also need to set config.i18n.fallbacks = true in all config/environments/*.rb files.