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

在前面的博文中，介绍了简单的CRUD风格的实现。

接下来我们在此基础上来实现一下RESTful版本的CRUD。

为什么要采用RESTful风格：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

 

尽量每一个controller值负责一组CRUD

下面开始实施

自动建立一组named routes对应到actions

編輯 /config/routes.rb，加入

 

map.resources :events

编辑/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的默认请求方法是 GET

对比一下原有的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' %>

 

编辑/app/views/events/show.html.erb

 

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

编辑/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的默认请求方法是POST

编辑/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 %>

运行一下看看吧~

总结一下HTTP请求跟action的4-7关系表：

 

其实HTML规格只支持GET/POST,不支持PUT和DELETE方法的，rails在生成HTML的时候偷偷的做了一些处理。

我们写的代码是这样的：

    <%##event_path默认是GET，删除需要指定:method##%><%= link_to 'delete', event_path(event), :method => :delete %>

生成的HTML是这样的：

<a οnclick="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>

当点击的时候，实际上在页面上生成了下面内容：

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

其实各种浏览器之间还有一些关于DELETE和PUT一些支持或者不支持的不统一现象，这些问题Rails处理掉了，我们不需要关注了。

另外，XmlHttpRequest（Ajax request）定义了GET/POST/PUT/DELETE/HEAD/OPTIONS

不过不是所有浏览器都支持。