Why locale setting in Rails acts as global (when using Thin)?

Question

I just realized that the recommended Rails way to set locale in your controller

before_filter :set_locale

def set_locale
  I18n.locale = params[:locale] || I18n         


        

Answer 1

Recommended code from above does not set locale globally it sets it by request.

before_filter :set_locale

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

Code is usually place in BaseController so before each page is render it is triggered and set. There is no race conditions since every page will trigger this code and I18n locale will be calculated there. You can expand this to let's say looks for users locale, than session locale, than request params, than uses English.

def set_locale
  I18n.locale = @user.locale || session[:locale] || params[:locale] || :en
end

In other words if you set local on one page let's say in home controller to german and got to dashboard controller you will see default language (english). Since change is not global. That is why code is placed in base controller. Hope it makes sense.