REST url generation for nested resources.

Hello everyone,

question:

   suppose program has_many episodes

    in the restful form_for ,

<% form_for (:episode,:url =>
@episode_path(@episode.program.id,@episode))

It looks redandant to me that why do i need to pass the two
parameters ,in which case only @episode is enough?

why rails do this? why not to save the first paramter?

thanks very much

Kevin