Вы можете переопределить сегмент пути, передав опцию :path
на ваш resources
вызов.
resources :songs, path: "songs/:artist_id"
это сгенерирует эти маршруты
songs GET /songs/:artist_id(.:format) {:action=>"index", :controller=>"songs"}
POST /songs/:artist_id(.:format) {:action=>"create", :controller=>"songs"}
new_song GET /songs/:artist_id/new(.:format) {:action=>"new", :controller=>"songs"}
edit_song GET /songs/:artist_id/:id/edit(.:format) {:action=>"edit", :controller=>"songs"}
song GET /songs/:artist_id/:id(.:format) {:action=>"show", :controller=>"songs"}
PUT /songs/:artist_id/:id(.:format) {:action=>"update", :controller=>"songs"}
DELETE /songs/:artist_id/:id(.:format) {:action=>"destroy", :controller=>"songs"}