Ruby on Rails Internationalization (I18n) Notes

My Locale Changes Randomly In Tests

Only tests ran through puma won’t affect locale of next test in line. Reset it after tests.

RSpec.configure do |config|
  config.after(:each) { I18n.locale = I18n.default_locale }
end

Run tests with the seed and debug where is fails:

RSpec.configure do |config|
  config.before(:each) do |example|
    puts "#{I18n.locale} #{example.metadata[:example_group][:file_path]} #{example.description}"
  end
end

bin/rspec --seed 53982

Required Settings

# config/application.rb

config.i18n.default_locale = ENV['DEFAULT_LOCALE'] || :en
config.i18n.available_locales = [:en, :sk]

Fragment Caching

Add locale to be part of the key:

- cache [I18n.locale, @article] do

Last Help

Sometimes deploy is just fucked up. Redeploy or restart containers.

My Fucking I18n Locale Leaks Across Requests

The locale isn’t reset in the same process or thread. So specific puma thread or unicorn process return the previous locale instead of expected default one.

Always set locale in before_action like:

# ApplicationController
before_action :set_locale

def set_locale
  if params[:locale]
    I18n.locale = params[:locale]
  else
    I18n.locale = I18n.default_locale
  end
end

Or use around_action like in Rails guides https://guides.rubyonrails.org/i18n.html#configure-the-i18n-module

# ApplucationController
around_action :switch_locale
 
def switch_locale(&action)
  locale = params[:locale] || I18n.default_locale
  I18n.with_locale(locale, &action)
end

If locale is invalid, it sets default one, so no need to validate against available locales.