Locales activation

The current locale - which is used for translation lookups or localizations - can be specified using the #locale= method (or #activate - both are equivalent):

I18n.locale = :fr
I18n.activate(:fr)

TIP

Locale changes like in the above example are always pseudo-global and are scopped to the current fiber.

Unless explicitly set, the default locale (en if not configured in I18n.config.default_locale) is used instead.

When activating a locale with #locale= or #activate, all further translations or localizations will be done using the specified locale. If the specified locale is not part of the available locales (either because it was not part of the loaded translations or because it was not part of the I18n.config.available_locales array), an I18n::Errors::InvalidLocale exception is raised.

Crystal I18n also provides the ability to execute a block with a specific locale activated. In order to do so, the #with_locale method can be used as follows:

I18n.with_locale(:fr) do
  I18n.t("simple.translation") # Will output a text in french
end

WARNING

#with_locale should be used over #locale= or #activate in most cases since it will ensure that the previously activated locale is activated again once the block execution finishes. This is especially relevant in the context of web requests processing where a locale matching a given HTTP request has to be activated. In this context, using #locale= could lead into subsequent requests using the previously activated locale if the later was not reset to its previous value after finishing processing the request.