ruby-on-rails - 在几个地方使用fields_for

Question

我有一个简单的模型

class Ad < ActiveRecord::Base
   has_many :ad_items
end

class AdItem < ActiveRecord::Base
   belongs_to :ad
end

我有一个“广告/新” View ，该 View 向我显示了创建新广告并向其中添加一些项目的表单

.html.erb代码如下所示:

<% form_for @ad, do |ad_form| %>
   <!-- some html -->

   <% ad_form.fields_for :ad_items do |f| %>
      <%= f.text_area "comment", :class => "comment", :rows => "5" %>
   <% end %>

   <!-- some other html -->

   <% ad_form.fields_for :ad_items do |f| %>
      <% render :partial => "detailed_item_settings", :locals => {:f => f} %>
   <% end %>
<% end %>

当广告包含一项时...

def new
   @ad = session[:user].ads.build

   # Create one item for the ad. Another items will be created on the
   # client side
   @ad.ad_items.build

   # standard stuff ...
end

...生成的HTML如下所示:

<form ... >
   <!-- some html -->

   <textarea id="ad_items_attributes_0_comment" name="ad[ad_items_attributes][0][comment]" />

   <!-- some other html -->

   <!-- "detailed_item_settings" partial's content -->
      <textarea id="ad_ad_items_attributes_1_desc" name="ad[ad_items_attributes][1][desc]" />
   <!-- end -->
</form>

如代码中所述，由于HTML结构的原因，我必须使用 fields_for 方法两次，因为我必须遵循HTML结构

对于第二个“fields_for”调用，“项目”的索引已经是1，而不是0，正如我期望的那样。

就像通过调用“fields_for”方法，一些内部计数器将增加...

但这是一个有点奇怪的行为...

我试图为fields_for设置:index => 0，但所有设置都保持不变...

怎么了

Answer 1

您可以为每个商品手动设置索引，但是您必须遍历商品才能获得商品索引:

  <% ad_form.fields_for :ad_items do |f| %>
     <%= f.text_area "comment", :class => "comment", :rows => "5" %>
  <% end %>
  ...
  <% ad_items.each_with_index do |item, i| %>
    <% ad_form.fields_for :ad_items, item, :child_index => i do |f| %>
      <% render :partial => "detailed_item_settings", :locals => {:f => f} %>
    <% end %>
  <% end %>