DRYing up repeating routes for several models

I have some models like News and Downloads which have_many comments :as => :commentable. Comment belongs_to :commentable and is :polymorphic. Like the comments, there are subscriptions. So my routes look like this:

resources :news do
  resources :comments do
    post :like, :on => :member
    delete :like, :on => :member
  end
  resources :subscriptions
  ...
end

resources :downloads do
  resources :comments do
    post :like, :on => :member
    delete :like, :on => :member
  end
  resources :subscriptions开发者_如何学JAVA
  ...
end

...

Is there a way to DRY this up? I tried defining

def comment_resources
  resources :comments do
    # ...
  end
  resources :subscriptions
end

at then top of routes.rb and then calling comment_resources but it seems dirty to me because it isn't namespaced / in a class correctly.

1) If you have exactly the same inner routes in both news and downloads, you can make

%w(news downloads).each do |res|
  resources res do
    resources :comments do
      post :like, :on => :member
      delete :like, :on => :member
    end
    resources :subscriptions
    ...
  end
end

2) Otherwise you can look at https://github.com/rails/routing_concerns (will be included as part of rails-4):

concern :commentable do
  resources :comments do
    post :like, :on => :member
    delete :like, :on => :member
  end
  resources :subscriptions
end

resources :news, concerns: :commentable do
  ...
end
resources :downloads, concerns: :commentable do
  ...
end

You were on the right track. You can define the method within the routes.draw do/end block so that it isn't tangling in the global namespace.

Application.routes.draw do
  def comment_resources
    resources :comments do
      post :like, :on => :member
      delete :like, :on => :member
    end
    resources :subscriptions
    ...
  end

  resources :downloads do
    comment_resources
  end

  resources :news do
    comment_resources
  end
end

taken from: http://symmetricinfinity.com/2013/04/16/drying-up-your-api-routes-in-rails.html