# 差
  get 'subscriptions/:id/unsubscribe'
  resources :subscriptions

  # 好
  resources :subscriptions do
   get 'unsubscribe', on: :member
  end

  # 差
  get 'photos/search'
  resources :photos

  # 好
  resources :photos do
   get 'search', on: :collection
  end

 resources :subscriptions do
   member do
    get 'unsubscribe'
    # 更多路由
   end
  end

  resources :photos do
   collection do
    get 'search'
    # 更多路由
   end
  end

 class Post < ActiveRecord::Base
   has_many :comments
  end

  class Comments < ActiveRecord::Base
   belongs_to :post
  end

  # routes.rb
  resources :posts do
   resources :comments
  end

  namespace :admin do
   # Directs /admin/products/* to Admin::ProductsController
   # (app/controllers/admin/products_controller.rb)
   resources :products
  end

  # 非常差
  match ':controller(/:action(/:id(.:format)))'