了解知识
 
在《Ruby on Rails,服务端如何响应页面提交的请求》中我们知道,页面提交给web服务器的请求先是尝试直接查找并返回public目录中的资源,如果没有找到则将请求交给Rails的Routes。Routes根据路由配置,将请求转化为对Controller中的Action并调用之。Routes的配置可说的细节很多,最开始我们先关注三种最简单的方式:Simple route,Default route,Root route。Routes的配置信息存放在config/routes.rb文件当中。
当前我的routes.rb文件如下所示,大段被注释掉的内容是各种配置用法的举例先不用理会,其中第二行get "demo/index"这句就是在《Ruby on Rails,创建最简单的视图/控制器单元Hello World》中通过调用生成视图/控制器命令被自动添加过来的。这就是一个Simple route。
在Routes配置文件中,越靠上的一行配置拥有越高的优先级。
 
SimpleSite::Application.routes.draw do  
  get "demo/index"  
  
  # The priority is based upon order of creation:  
  # first created -> highest priority.  
  
  # Sample of regular route:  
  #   match 'products/:id' => 'catalog#view'  
  # Keep in mind you can assign values other than :controller and :action  
  
  # Sample of named route:  
  #   match 'products/:id/purchase' => 'catalog#purchase', :as => :purchase  
  # This route can be invoked with purchase_url(:id => product.id)  
  
  # Sample resource route (maps HTTP verbs to controller actions automatically):  
  #   resources :products  
  
  # Sample resource route with options:  
  #   resources :products do  
  #     member do  
  #       get 'short'  
  #       post 'toggle'  
  #     end  
  #  
  #     collection do  
  #       get 'sold'  
  #     end  
  #   end  
  
  # Sample resource route with sub-resources:  
  #   resources :products do  
  #     resources :comments, :sales  
  #     resource :seller  
  #   end  
  
  # Sample resource route with more complex sub-resources  
  #   resources :products do  
  #     resources :comments  
  #     resources :sales do  
  #       get 'recent', :on => :collection  
  #     end  
  #   end  
  
  # Sample resource route within a namespace:  
  #   namespace :admin do  
  #     # Directs /admin/products/* to Admin::ProductsController  
  #     # (app/controllers/admin/products_controller.rb)  
  #     resources :products  
  #   end  
  
  # You can have the root of your site routed with "root"  
  # just remember to delete public/index.html.  
  # root :to => 'welcome#index'  
  
  # See how all your routes lay out with "rake routes"  
  
  # This is a legacy wild controller route that's not recommended for RESTful applications.  
  # Note: This route will make all actions in every controller accessible via GET requests.  
  # match ':controller(/:action(/:id))(.:format)'  
end  
get "demo/index"的意思是将demo/index的请求调用名为demo的Controller中名为index的Action。
[ruby] view plaincopy
match "demo/index", :to => "demo#index"  
这种路由配置最简单易懂但是比较不易于维护,因为我们要在每次增加视图/控制器时维护Routes配置。我们想使用一个更加通用的规则,在这个规则的帮助下我们修改视图/控制器规则后依然能够工作-Default route。
get /:controller/:action/:id的意思是调用名为demo的Controller中名为index的Action并传入id值。
[ruby] view plaincopy
match ':controller(/:action(/:id(.:format)))'  
routes.rb文件的最下面也就是优先级最低的一条配置既是Default route规则。如果传入的请求没有能够匹配Routes配置中的任何一条规则,则将按照这一条规则对请求进行解析。我们将这条规则前的注释符号删除,以便启用这条规则,同时也就不需要文件顶部的那条get "demo/index"。
 
SimpleSite::Application.routes.draw do  
  match ':controller(/:action(/:id))(.:format)'  
end  
修改了routes.rb之后需要重启服务器。请求“localhost:3000/demo/index”依然能够转向之前的页面,说明Default route配置包含了之前Simple route的情况。
由于我们之前删除了public目录中的index.html,所以当以“localhost:3000/”请求时将没有规则能够匹配“/”。
 
这时,我们需要配置Root route。
[ruby] view plaincopy
root :to => "demo#index"  
此时route.rb如下
[ruby] view plaincopy
SimpleSite::Application.routes.draw do  
  root :to => "demo#index"    
  match ':controller(/:action(/:id))(.:format)'  
end  
重启服务器后访问“localhost:3000/”得到了配置中规定的页面。
 
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