Rails I18n validation deprecation warning

I just updated to rails 4.0.2 and I'm getting this warning:


[deprecated] I18n.enforce_available_locales will default to true in the future. If you really want to skip validation of your locale you can set I18n.enforce_available_locales = false to avoid this message.

Is there any security issue in setting it to false?

Important: Make sure your app is not using I18n 0.6.8, it has a bug that prevents the configuration to be set correctly.

Short answer

In order to silence the warning edit the application.rb file and include the following line inside the Rails::Application body

config.i18n.enforce_available_locales = true

The possible values are:

• false: if you

• want to skip the locale validation

• don't care about locales

• true: if you

• want the application to raise an error if an invalid locale is passed (or)

• want to default to the new Rails behaviors (or)

• care about locale validation

Note:

• The old default behavior corresponds to false, not true.

• If you are setting the config.i18n.default_locale configuration or other i18n settings, make sure to do it after setting the config.i18n.enforce_available_locales setting.

• If your use third party gems that include I18n features, setting the variable through the Application config object, may not have an effect. In this case, set it directly to I18n using I18n.config.enforce_available_locales.

Caveats

Example

require File.expand_path('../boot', __FILE__)

# ...

module YouApplication
  class Application < Rails::Application

    # ...

    config.i18n.enforce_available_locales = true
    # or if one of your gem compete for pre-loading, use
    I18n.config.enforce_available_locales = true

    # ...

  end
end

Long answer

The deprecation warning is now displayed both in Rails 4 (>= 4.0.2) and Rails 3.2 (>= 3.2.14). The reason is explained in this commit.


Enforce available locales


When I18n.config.enforce_available_locales is true we'll raise an
I18n::InvalidLocale exception if the passed locale is unavailable.


The default is set to nil which will display a deprecation error.


If set to false we'll skip enforcing available locales altogether (old behaviour).


This has been implemented in the following methods :

• I18n.config.default_locale=

• I18n.config.locale=

• I18n.translate

• I18n.localize

• I18n.transliterate

Before this change, if you passed an unsupported locale, Rails would silently switch to it if the locale is valid (i.e. if there is a corresponding locale file in the /config/locales folder), otherwise the locale would default to the config.i18n.default_locale configuration (which defaults to :en).

The new version of the I18n gem, forces developers to be a little bit more conscious of the locale management.

In the future, the behavior will change and if a locale is invalid, the Rails app will raise an error.

In preparation of such change (that may potentially break several applications that until today were relying on silent defaults), the warning is forcing you to explicitly declare which validation you want to perform, during the current transition period.

To restore the previous behavior, simply set the following configuration to false

config.i18n.enforce_available_locales = false

otherwise, set it to true to match the new Rails defaults or if you want to be more rigid on domain validation and avoid switching to the default in case of invalid locale.

config.i18n.enforce_available_locales = true

Caveat

-
If you are setting the config.i18n.default_locale configuration or using any of the previously mentioned methods (default_locale=, locale=, translate, etc), make sure to do it after setting the config.i18n.enforce_available_locales setting. Otherwise, the deprecation warning will keep on popping up. (Thanks Fábio Batista).

-
If you use third party gems that include I18n features, setting the variable through may not have effect. In fact, the issue is the same as described in the previous point, just a little bit harder to debug.

This issue is a matter of precedence. When you set the config in your Rails app, the value is not immediately assigned to the I18n gem. Rails stores each config in an internal object, loads the dependencies (Railties and third party gems) and then it passes the configuration to the target classes. If you use a gem (or Rails plugin) that calls any of the I18n methods before the config is assigned to I18n, then you'll get the warning.

In this case, you need to skip the Rails stack and set the config immediately to the I18n gem by calling

I18n.config.enforce_available_locales = true

instead of

config.i18n.enforce_available_locales = true

The issue is easy to prove. Try to generate a new empty Rails app and you will see that setting config.i18n in the application.rb works fine.

If in your app it does not, there is an easy way to debug the culprit. Locate the i18n gem in your system, open the i18n.rb file and edit the method enforce_available_locales! to include the statement puts caller.inspect.

This will cause the method to print the stacktrace whenever invoked. You will be able to determine which gem is calling it by inspecting the stacktrace (in

Stack Overflow Q#20361428, score: 617