Ruby on Rails 之旅（七）—— Ruby on Rails 入門（4）

在前面的博文中，介紹了簡單的CRUD風格的實現。

接下來咱們在此基礎上來實現一下RESTful版本的CRUD。

爲何要採用RESTful風格：designing controller and action is chaos

 

HTTP methods (RFC 2616)

POST -> Create 

GET -> Read 

PUT -> Update 

DELETE -> Delete

 

Remove actions from URL, and we have simple named route.

/events/create -> POST /events

/events/show/1 -> GET /events/1

/events/update/1 -> PUT /events/1

/events/destroy/1 -> DELETE /events/1

 

CRUD-based action names get things simpler

create  -> POST 

show -> GET 

PUT -> update

delete -> DELETE

 

儘可能每個controller值負責一組CRUD

下面開始實施

自動創建一組named routes對應到actions

編輯 /config/routes.rb，加入

 

map.resources :events

編輯/app/views/events/index.html.erb

<ul>
  <%= will_paginate @events %>
  <% @events.each do |event| %>
  <li>
    <%= link_to event.name, event_path(event) %>
    <%= link_to 'edit', edit_event_path(event) %>
    <%= link_to 'delete', event_path(event), :method => :delete %>
  </li>
  <% end -%>
  <%= will_paginate @events %>
</ul>
<%= link_to 'new event', :controller => 'events', :action => 'new' %> 

event_path的默認請求方法是 GET

對比一下原有的souce

<ul>
  <%= will_paginate @events %>
  <% @events.each do |event| %>
  <li>  
    <%= link_to event.name, :controller => 'events', :action => 'show', :id => event %>
    <%= link_to 'edit', :controller => 'events', :action => 'edit', :id => event %>
    <%= link_to 'delete', :controller => 'events', :action => 'destroy', :id => event %>
  </li>
  <% end -%>
  <%= will_paginate @events %>
</ul>
<%= link_to 'new event', :controller => 'events', :action => 'new' %>

 

編輯/app/views/events/show.html.erb

 

<%=h @event.name %>
<%=h @event.description %>
<p>
  <%= link_to 'back to index', events_path %>
</p>

編輯/app/views/events/new.html.erb

 

<%= error_messages_for :event %>
<% form_for @event, :url => events_path do |f| %>
<%= render :partial => 'form', :locals => { :f => f } %>
<%= f.submit "Create" %>
<% end %>

在Form中events_path的默認請求方法是POST

編輯/app/views/events/edit.html.erb

 

<%= error_messages_for :event %>
<% form_for @event, :url => event_path(@event), :html => { :method => :put } do |f| %>
<%= render :partial => 'form', :locals => { :f => f } %>
<%= f.submit "Update" %>
<% end %>

運行一下看看吧~

總結一下HTTP請求跟action的4-7關係表：

 

其實HTML規格只支持GET/POST,不支持PUT和DELETE方法的，rails在生成HTML的時候偷偷的作了一些處理。

咱們寫的代碼是這樣的：

<%##event_path默認是GET，刪除須要指定:method##%>
    <%= link_to 'delete', event_path(event), :method => :delete %>

生成的HTML是這樣的：

<a onclick="var f = document.createElement('form'); f.style.display = 'none'; this.parentNode.appendChild(f); f.method = 'POST'; f.action = this.href;var m = document.createElement('input'); m.setAttribute('type', 'hidden'); m.setAttribute('name', '_method'); m.setAttribute('value', 'delete'); f.appendChild(m);var s = document.createElement('input'); s.setAttribute('type', 'hidden'); s.setAttribute('name', 'authenticity_token'); s.setAttribute('value', 'TwKvS1qYjCaO2RQ3QlCdo3K57NfH0yTqKShmMk8jjI0='); f.appendChild(s);f.submit();return false;" href="/events/1">delete</a>

當點擊的時候，實際上在頁面上生成了下面內容：

<form id="edit_events_1" method="post" action="/events/1">
<input type="hidden" value="put" name="_method"/>
....
</form>

其實各類瀏覽器之間還有一些關於DELETE和PUT一些支持或者不支持的不統一現象，這些問題Rails處理掉了，咱們不須要關注了。

另外，XmlHttpRequest（Ajax request）定義了GET/POST/PUT/DELETE/HEAD/OPTIONS

不過不是全部瀏覽器都支持。