has_many構文は、ブロック構文が気に入らなかった人の省略形としてRails2に追加されたものだと思います。あなたはそれについてのブログ投稿をここで見ることができます。試したところ、Rails3はhas_manyオプションを無視しているようです。したがって、私にとっての出力は次のとおりです。
resources :schools do
resources :documents
end
ルートを作成しました:
school_documents GET /schools/:school_id/documents(.:format) {:action=>"index", :controller=>"documents"}
POST /schools/:school_id/documents(.:format) {:action=>"create", :controller=>"documents"}
new_school_document GET /schools/:school_id/documents/new(.:format) {:action=>"new", :controller=>"documents"}
edit_school_document GET /schools/:school_id/documents/:id/edit(.:format) {:action=>"edit", :controller=>"documents"}
school_document GET /schools/:school_id/documents/:id(.:format) {:action=>"show", :controller=>"documents"}
PUT /schools/:school_id/documents/:id(.:format) {:action=>"update", :controller=>"documents"}
DELETE /schools/:school_id/documents/:id(.:format) {:action=>"destroy", :controller=>"documents"}
schools GET /schools(.:format) {:action=>"index", :controller=>"schools"}
POST /schools(.:format) {:action=>"create", :controller=>"schools"}
new_school GET /schools/new(.:format) {:action=>"new", :controller=>"schools"}
edit_school GET /schools/:id/edit(.:format) {:action=>"edit", :controller=>"schools"}
school GET /schools/:id(.:format) {:action=>"show", :controller=>"schools"}
PUT /schools/:id(.:format) {:action=>"update", :controller=>"schools"}
DELETE /schools/:id(.:format) {:action=>"destroy", :controller=>"schools"}
その間
resources :schools :has_many => :documents
ルートを作成しました:
schools GET /schools(.:format) {:action=>"index", :controller=>"schools"}
POST /schools(.:format) {:action=>"create", :controller=>"schools"}
new_school GET /schools/new(.:format) {:action=>"new", :controller=>"schools"}
edit_school GET /schools/:id/edit(.:format) {:action=>"edit", :controller=>"schools"}
school GET /schools/:id(.:format) {:action=>"show", :controller=>"schools"}
PUT /schools/:id(.:format) {:action=>"update", :controller=>"schools"}
DELETE /schools/:id(.:format) {:action=>"destroy", :controller=>"schools"}
あなたの質問に対する本当の答えは、それらが同じことをするはずであるということだと思いますが、構文が異なります。