我的应用由四个模型组成。用户>列表>愿望<项目。我在首页上展示了所有项目，并希望能够从各个项目中建立一个愿望。
由于关联，我必须允许用户指定他想要将项目与哪个列表关联。我想通过 ajax 调用和模态来完成。item但是，partial中的实例变量_item.html.erb不能通过 a 传递link_to，它调用app/views/wishes/new.js.erb，它呈现一个表单来指定列表。
我对rails和ruby很陌生，这个问题已经困扰我好几天了！非常感谢任何帮助。
协会：
class User < ActiveRecord::Base
has_many :lists, dependent: :destroy
has_many :wishes, through: :lists
has_many :items, through: :wishes
end
class List < ActiveRecord::Base
belongs_to :user
has_many :wishes, dependent: :destroy
has_many :items, through: :wishes
end
class Wish < ActiveRecord::Base
belongs_to :list, touch: true
belongs_to :item
end
class Item < ActiveRecord::Base
has_many :wishes
has_many :lists, through: :wishes
end
app/views/static_pages/home.html.erb
<%= render @items %>
应用程序/视图/项目/_item.html.erb
<div class="span4">
<div class="white-box item">
<div class="image-container">
<%= link_to "Wishlistt it", new_wish_path(item_id: item.id), id: "new_wish", class: "btn btn-primary btn-large", remote: true %>
<a href="<%= item_path(item) %>" class="item-link">
<em class="mark"></em>
<%= image_tag item.image_url(:medium).to_s %>
</a>
</div>
<h3><%= item.title %></h3>
<%= item.wishes.count %> wishes this item
</div>
</div>
应用程序/视图/愿望/new.js.erb
$('body').append('<%= j render "new_wish" %>');
$('#new_wish').modal('toggle')
应用程序/视图/愿望/_new_wish.html.erb
<div id="new_wish" class="modal hide fade" tabindex="1" role="dialog" aria-labelledby="make_wish" aria-hidden="true">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal" aria-hidden="true">×</button>
<h3 id="wishlistt_it">Wishlistt it</h3>
</div>
<div id="linkpreview">
<div class="modal-body">
<%= form_for(@item.wishes.build(item_id: @item.id)) do |f| %>
<%= f.hidden_field :item_id %>
<%= f.label :list_id %>
<%= select_tag :list_id, options_for_select(current_user.lists.all.collect{ |u| [u.name, u.id] }) %>
<%= f.submit "Add wish", class: "btn btn-large btn-primary" %>
<% end %>
</div>
<div class="modal-footer">
<button class="btn" data-dismiss="modal" aria-hidden="true">Close</button>
<%= link_to "Get info", new_item_path, id: "urlb", class: "btn btn-primary", remote: true %>
</div>
</div>
</div>
按来自的链接_item.html.erb会引发此错误：
undefined method `wishes' for nil:NilClass
编辑
wish_controller.rb
class WishesController < ApplicationController
before_filter :signed_in_user, only: [:create, :destroy]
before_filter :correct_user, only: :destroy
def new
@wish = Wish.new
end
def create
@item = Item.find_by_id(params[:item_id])
@wish = Wish.create!(item_id: params[:wish][:item_id], list_id: params[:list_id])
redirect_to root_url
end
def destroy
@wish.destroy
redirect_to current_user
end
private
def correct_user
@wish = current_user.wishes.find_by_id(params[:id])
redirect_to current_user if @wish.nil?
end
end