rails render partial 参数 变量说明

这里的conventions总是容易记不清楚 就是locals collection object 

1. 默认参数 

 <%= render :partial => "account" %>

默认本地有个变量@account, 传递过去，render到的partial（_account.erb）有个变量account 

2. 单独参数 locals 
locals传递一组hash参数hash 值是本地的变量，hash的key是partial里的变量 

 <%= render :partial => "account", :locals => { :account => @buyer } %>

 <% for ad in @advertisements %>
   <%= render :partial => "ad", :locals => { :ad => ad } %>
 <% end %>

上面两个render分别 
传递本地变量@buyer到_account.erb里叫account的参数 
传递本地变量ad到_ad.erb里叫ad 

3 

根据1默认参数下面两个是一样的 

 <%= render :partial => "contract", :locals => { :contract  => @contract } %>

 <%= render :partial => "contract" %>

4. as使用 

用来改变传递之后，partial里变量的名称，如下，render方式是一样的。 

 <%= render :partial => "contract", :as => :agreement

 <%= render :partial => "contract", :locals => { :agreement => @contract }

传递@contract到_contract.erb里，partial里的变量名为agreement 

5. object使用 

object最简单，就是把一个变量原名传递到partial里，  
所以什么都记不清楚的时候，就用object多写点都能表达 

如下： 

 <%= render :partial => "account", :object => @buyer %>

 <% for ad in @advertisements %>
   <%= render :partial => "ad", :object => ad %>
 <% end %>

传递@buyer到_account.erb的partial里变量名还是@buyer 
传递ad到_ad.erb的partial里变量名还是ad 

6 object和as合用 

 <%= render :partial => "contract", :object => @contract, :as => :contract %>

 <%= render :partial => "contract" %>

7 collection 

 <%= render :partial => "ad", :collection => @advertisements %>

@advertisements是一个array，partial里_ad.erb有个ad变量是@advertisements的成员。就是_ad.erb不用写loop只是一条广告显示。 

 <%= render :partial => "ad", :collection => @advertisements, :spacer_template => "ad_divider" %>

同上，循环显示_ad.erb _ad_divider.erb 显示@advertisements.size次其中partial_ad_counter是默认计数器表示第几条广告 

8 默认 

看你要partial的变量是一组记录还是一条记录，会对应约定用locals和collection 

 #@account是一条记录
 # <%= render :partial => "accounts/account", :locals => { :account => @account} %>
 <%= render :partial => @account %>

 # @posts是一组记录
 # <%= render :partial => "posts/post", :collection => @posts %>
 <%= render :partial => @posts %>

这是很人性的约定，可有时候就是忘了 

9 一些漂亮的简写 

 #<%= render :partial => "account" %>可用下面代替
 <%= render "account" %>

 #<%= render :partial => "account", :locals => { :account => @buyer } %>可用下面代替
 <%= render "account", :account => @buyer %>

 # @account是一条记录
 # <%= render :partial => "accounts/account", :locals => { :account => @account } %>可用下面代替
 <%= render(@account) %>

 # @posts是一组记录
 # <%= render :partial => "posts/post", :collection => @posts %>可用下面代替
 <%= render(@posts) %>

10 layout 

 <%# app/views/users/index.html.erb &>
 Here's the administrator:
 <%= render :partial => "user", :layout => "administrator", :locals => { :user => administrator } %>

 Here's the editor:
 <%= render :partial => "user", :layout => "editor", :locals => { :user => editor } %>

 <%# app/views/users/_user.html.erb &>
 Name: <%= user.name %>

 <%# app/views/users/_administrator.html.erb &>
 <div id="administrator">
   Budget: $<%= user.budget %>
   <%= yield %>
 </div>

 <%# app/views/users/_editor.html.erb &>
 <div id="editor">
   Deadline: <%= user.deadline %>
   <%= yield %>
 </div>

参考文档： 
http://apidock.com/rails/ActionController/Base/render 
http://johnnyhg.iteye.com/blog/499182 
http://apidock.com/rails/ActionView/Helpers/UrlHelper/link_to