如何在rails 3中的路由中设置默认参数值

如何在Rails 3中设置路由中的默认参数值。例如,我有这条路线

match ':slug/:id/:direction' => 'quiz#show', :as => :quiz_details, :direction => "next" 

我想将方向的值默认为next

 match ':slug/:id/:direction' => 'quiz#show', :as => :quiz_details, :defaults => { :direction => "next" } 

官方Rails指南中的更多细节。