Question

我正在尝试使用Cocoon Gem构建嵌套表单。但是我得到的错误如下所示。我在这里找到了另一个回答的问题Rails Cocoon Gem: Undefined Method 'new_record?' on link_to_remove_association with Wicked。但是，从模型代码中可以看出，唯一的答案已被排除。

错误

 ActionView::Template::Error (undefined method `new_record?' for nil:NilClass):
        1: <div class="nested-fields">
        2:      <%=f.input :name%>
        3:      <%= link_to_remove_association "remove task", f%>
        4: </div>
      app/views/templates/_room_fields.html.erb:3:in `_app_views_templates__room_fields_html_erb__1867913568926009508_70125979350780'
      app/views/templates/_form.html.erb:5:in `block (2 levels) in _app_views_templates__form_html_erb__4123974558704004784_70125994949300'
      app/views/templates/_form.html.erb:4:in `block in _app_views_templates__form_html_erb__4123974558704004784_70125994949300'
      app/views/templates/_form.html.erb:1:in `_app_views_templates__form_html_erb__4123974558704004784_70125994949300'
      app/views/templates/new.html.erb:1:in `_app_views_templates_new_html_erb___3689493092838604682_70125964273280'Models

模型

 class Template < ActiveRecord::Base
      has_many :rooms
      accepts_nested_attributes_for :rooms, :allow_destroy => true
    end
 class Room < ActiveRecord::Base
      belongs_to :template
      has_many :items
      accepts_nested_attributes_for :items, :allow_destroy => true
    end
 class Item < ActiveRecord::Base
      belongs_to :room
    end

表单视图

<%= simple_form_for @template do |f| %>
    <%= f.input :name%>
    <div id="rooms">
        <%= simple_fields_for :rooms do |room| %>
            <%= render 'room_fields',:f => room %>
        <%end%>
        <div class="links">
            <%= link_to_add_association 'add room', f, :rooms%>
        </div>
    </div>
<%end%>

Room Partial

<div class="nested-fields">
        <%=f.input :name%>
        <%= link_to_remove_association "remove task", f%>
</div>

控制器

class TemplatesController < ApplicationController
  def new
    @template = Template.new
  end

  def create
  end
end

Answer 1

此处的错误是simple_fields_for未链接到表单对象。所以写

<%= f.simple_fields_for :rooms do |room| %>

Answer 2

Cocoon正在尝试执行f.object.new_record?，并且从显示的错误消息中可以看出，f.object显然是nil。

我发现问题出在new行动中。您已构建了一个空白的Template对象，但没有与之关联的room。你必须这样做 -

def new
  @template = Template.new
  @template.rooms.build
end

Cocoon Gem：未定义的方法`new_record？' for nil：link_to_remove_association上的NilClass

2 个答案: