Cocoon Gem: undefined method `new_record?' for nil:NilClass on link_to_remove_association

问题

I am trying to build a nested form with the Cocoon Gem. however i am getting the error as shown below. I found another answered question here that Rails Cocoon Gem: Undefined Method 'new_record?' on link_to_remove_association with Wicked. However the only answer has already been ruled out as you can see from my model code.

Error

 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

Models

 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

Form View

<%= 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>

Controller

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

  def create
  end
end

回答1:

The error here is that the simple_fields_for is not linked to the form-object. So write

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

回答2:

Cocoon is trying to execute f.object.new_record? and from the error message you are shown, it is clear that f.object is nil.

I see that the problem is in the new action. You have built a blank Template object, but there isn't any room associated with it. You have to do this -

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

来源：https://stackoverflow.com/questions/19238720/cocoon-gem-undefined-method-new-record-for-nilnilclass-on-link-to-remove-as

标签

ruby-on-rails

ruby

ruby-on-rails-4

cocoon-gem