div class=nested-fields div class=form-group label for=title class=col-sm-2 control-labelSKU名称label = ftext_field title class form-control div div class=form-group label for=description c

错误是因为在代码中使用了<%= f.id %>，但是f并没有一个id方法。您可能想要使用f.object.id来获取关联对象的id。

修改后的代码如下所示：

<div class="nested-fields">
  <div class="form-group">
    <label for="title" class="col-sm-2 control-label">SKU名称</label>
    <%= f.text_field :title, class: "form-control" %>
  </div>

  <div class="form-group">
    <label for="description" class="col-sm-2 control-label">SKU描述</label>
    <%= f.text_field :description, class: "form-control" %>
  </div>

  <div class="form-group">
    <label for="price" class="col-sm-2 control-label">单价</label>
    <%= f.text_field :price, class: "form-control" %>
  </div>

  <div class="form-group">
    <label for="stock" class="col-sm-2 control-label">库存</label>
    <%= f.text_field :stock, class: "form-control" %>
  </div>
  <input type="hidden" name="id" value="<%= f.object.id %>">
  <%= link_to_remove_association "Remove SKU", f %>
</div>

这样，f.object.id将返回关联对象的id