Rails 2 -> Rails 3 Routing Examples

### Basic routes ###

Rails 2:
    # singular resource
    map.resource :account

    # resources with addition member & collection actions 
    map.resources :games, :member => { :download => :get }, :collection => { :favourites => :get }

Rails 3:
    # singular resource
    resource :account

    # resources with addition member & collection actions
    resources :games do
      get :download,  :on => :member
      get :favourites, :on => :collection
    end

    # If you have multiple member/collection actions they can be grouped via blocks    
    resources :games do
      member do
        get :download
        put :refresh_achievements
      end

      collection do
        get   :favourites
        get   :wish_list
        get   :owned_by_friends
      end
    end

### Defining root mappings ###

Rails 2:
    # http://localhost:3000/
    map.root :controller => 'posts', :action => 'index'

    # http://localhost:3000/admin
    map.namespace :admin do |admin|
      admin.root :controller => 'posts'
    end

Rails 3:
    # http://localhost:3000/
    root :to => 'Posts#index'

    # http://localhost:3000/admin
    namespace :admin do
      root :to => "Admin::Posts#index"
    end

    # OR
    # http://localhost:3000/admin
    namespace :admin do
      root :to => "admin/posts#index"
    end

One thing to note is that if you are defining a root mapping in a namespace, it doesn't make any assumptions that the controller is in the same namespace in Rails 3.

### Optional params ###

Rails 2:

    # Allows a mapping to be associated with multiple routes eg:
    # http://localhost:3000/posts/2010
    # http://localhost:3000/posts/2010/01
    map.connect 'posts/:year/:month', :controller => 'posts', :month => nil, :requirements => { :year => /\d{4}/ }

Rails 3:
    # Allows a mapping to be associated with multiple routes eg:
    # http://localhost:3000/posts/2010
    # http://localhost:3000/posts/2010/01
    match 'posts/:year(/:month)' => 'Posts#index', :constraints => { :year => /\d{4}/ }

You'll notice that this mapping also makes use of the :constraints option rather than :requirements which would be found in a Rails 2 app.

Thanks for this - I've forked it for reference - always handy to have on hand.