Detect browser language in Rails

Question

How do you detect the users language (in RoR) as set in the browser? I will have a select box the user can use at anytime, but I\'d like to default to whatever their browser

Answer 1

This is a really old question, but I like to mention that Rails guide has a description of how to detect user browser language.

Below code is based on the solution from Ruby on Rails guide with improvements:

• checks are there HTTP_ACCEPT_LANGUAGE - sometimes that header is missing for bots, and you will get errors in your error reporting tool
• checks are language supported by your application

code:

  def set_locale_based_on_browser
    locale = extract_locale_from_accept_language_header

    I18n.locale =
      if locale_valid?(locale)
        locale
      else
        :en
      end
  end

  private

  def locale_valid?(locale)
    I18n.available_locales.map(&:to_s).include?(locale)
  end

  def extract_locale_from_accept_language_header
    accept_language = request.env['HTTP_ACCEPT_LANGUAGE']
    return unless accept_language

    accept_language.scan(/^[a-z]{2}/).first
  end
end

More information about locale detection can be found in Ruby on Rails guide: https://guides.rubyonrails.org/i18n.html#choosing-an-implied-locale