    def add_sort_option(options, field, direction, prepend = false)
      if driver == :mongo
        sorting = (options[:sort] || []).dup
        sort_params = [field, direction]
        prepend ? sorting.unshift(sort_params) : sorting.push(sort_params)
      else
        sorting = (options[:sort] || {}).dup
        prepend ? sorting = { field => direction }.merge(sorting) : sorting[field] = direction
      end
      options.store(:sort, sorting)
    end