translation_logger.rb

# monkey patch I18n to log used/missing translations                                                      

I18n.module_eval do

  class << self

    def my_logger
      filename = File.join(RAILS_ROOT, %w(log translations.log))
      @my_logger ||= Logger.new(File.open(filename, 'a'))
    end

    def log(msg)
      my_logger.info msg
    end

    def my_exception_handler(exception, locale, key, options)
      if I18n::MissingTranslationData === exception
        log exception.message
        return exception.message
      end
      raise exception
    end

    # def translate(key, options = {})                                                                    
    #   locale = options.delete(:locale) || I18n.locale                                                   
    #   translation = backend.translate locale, key, options                                              
    #   log("found translation: (#{locale}) #{key} #{options.inspect}")                                   
    #   return translation                                                                                
    # rescue I18n::ArgumentError => e                                                                     
    #   raise e if options[:raise]                                                                        
    #   my_exception_handler e, locale, key, options                                                      
    # end                                                                                                 

  end

end

I18n.exception_handler = :my_exception_handler                                                          

I18n.log('started. load path...')
I18n.log(I18n.load_path * "\n")
I18n.log('logging...')