def sort(*ordering)
      resource = all
      ordering.compact!
      ordering.flatten!
      return resource if ordering.size == 0
      
      ordering.each do |order|
        order = Array(order)

        order.each do |column_or_relation, options|
          if column_or_relation.to_sym == :random
            resource = resource.random_sort
          elsif self.column_names.include?(column_or_relation.to_s)
            resource = resource.sort_for_column(column_or_relation, options)
          elsif reflect_on_association(column_or_relation.to_sym)
            resource = resource.select(resource.klass.arel_table[Arel::Nodes::SqlLiteral.new('*')])
            resource = resource.sort_for_relation(column_or_relation.to_sym, options)
          else
            raise ActiveRecord::StatementInvalid.new("Unkown column #{column_or_relation}")
          end
        end
      end

      resource
    end
def sort(*ordering)
      resource = all
      ordering.compact!
      ordering.flatten!
      return resource if ordering.size == 0
      
      ordering.each do |order|
        order = Array(order)

        order.each do |column_or_relation, options|
          if column_or_relation.to_sym == :random
            resource = resource.random_sort
          elsif self.column_names.include?(column_or_relation.to_s)
            resource = resource.sort_for_column(column_or_relation, options)
          elsif reflect_on_association(column_or_relation.to_sym)
            resource = resource.select(resource.klass.arel_table[Arel::Nodes::SqlLiteral.new('*')])
            resource = resource.sort_for_relation(column_or_relation.to_sym, options)
          else
            raise ActiveRecord::StatementInvalid.new("Unkown column #{column_or_relation}")
          end
        end
      end

      resource
    end
class << self
 ordering:
 :id
 :name, :id
 :id => :desc
 :id => {:desc => :nulls_last}
 :listings => :id
 :listings => {:id => {:asc => :nulls_first}}
 :random