set_i18n_locale_from_browser

gistfile1.txt

class ApplicationController < ActionController::Base
  before_action :set_locale

  private

  def set_locale
    if current_user
      if !current_user.locale.present?
        set_i18n_locale_from_browser
        current_user.update(locale: I18n.locale.to_s)
      end
      I18n.locale = current_user.locale
    else
      set_i18n_locale_from_browser
    end
  end

  def set_i18n_locale_from_browser
    old_locale = I18n.locale
    begin
      locale = (accept_locale(env) || I18n.default_locale).to_s
      unless I18n.locale_available? locale
        locale = locale.gsub(/(?<=-).+/, /(?<=-).+/.match(locale).to_s.upcase)
      end
      env['rack.locale'] = I18n.locale = locale
      response.headers['Content-Language'] = locale unless response.headers['Content-Language']
    ensure
      I18n.locale = old_locale
    end
  end

  def accept_locale(env)
    accept_langs = env["HTTP_ACCEPT_LANGUAGE"]
    return if accept_langs.nil?

    languages_and_qvalues = accept_langs.split(",").map { |l|
      l += ';q=1.0' unless l =~ /;q=\d+(?:\.\d+)?$/
      l.split(';q=')
    }

    lang = languages_and_qvalues.sort_by { |(locale, qvalue)|
      qvalue.to_f
    }.last.first

    lang == '*' ? nil : lang
  end
end