reverse_sql_order

# File activerecord/lib/active_record/relation/query_methods.rb, line 977
    def reverse_sql_order(order_query)
      order_query = ["#{quoted_table_name}.#{quoted_primary_key} ASC"] if order_query.empty?

      order_query.flat_map do |o|
        case o
        when Arel::Nodes::Ordering
          o.reverse
        when String
          o.to_s.split(',').collect do |s|
            s.strip!
            s.gsub!(/\sasc\Z/, ' DESC') || s.gsub!(/\sdesc\Z/, ' ASC') || s.concat(' DESC')
          end
        when Symbol
          { o => :desc }
        when Hash
          o.each_with_object({}) do |(field, dir), memo|
            memo[field] = (dir == :asc ? :desc : :asc )
          end
        else
          o
        end
      end
    end