通过关联has_many嵌套属性的 Rails 嵌套属性不创建

Question

我试图提供一种方法，在一个模型中生成一个新对象（列表），在另一个模型中使用has_many关系（通过分组）生成一个新的关联对象（项目）。我能够让表单工作正常，但无法弄清楚为了正确完成创建过程，我缺少什么。

Rails v.5.1.2，Ruby v.2.4.1

lists_controller.rb

    def new
    @list = current_user.lists.new
     3.times { @list.items.build }
    end

    def create
    @list = current_user.lists.new(list_params)
    respond_to do |format|
    if @list.save
    format.html { redirect_to @list, notice: 'List was successfully created.' }
    format.json { render :show, status: :created, location: @list }
    else
    format.html { render :new }
    format.json { render json: @list.errors, status: :unprocessable_entity }
    end
   end
  end

  private
  def set_list
   @list = List.find(params[:id])
  end

 def correct_user
  @list = current_user.lists.find_by(id: params[:id])
  redirect_to lists_path, notice: "Not authorized to edit this list" 
 if @list.nil?
 end


def list_params
  params.require(:list).permit(:title, {
    item_attributes: [
             :id, :title, :url
          ]})
end

items_controller.rb

     def new
       @item = Item.new
     end

    private

     def set_item
      @item = Item.find(params[:id])
     end


    def item_params
       params.require(:item).permit(:title, :body, :url, :created, 
     :list_ids => [])
      end
     end

list.rb模型

 has_many :groupings, :dependent => :destroy 
 has_many :items, :through => :groupings

 accepts_nested_attributes_for :items,

 reject_if: ->(attrs) { attrs['title'].blank? || attrs['url'].blank? }

item.rb模型

 has_many :groupings, :dependent => :destroy
 has_many :lists, :through => :groupings
 validate :has_lists?
  accepts_nested_attributes_for :lists

 attr_writer :list_titles
 after_save :assign_lists

  def list_titles
   @list_titles || lists.map(&:title).join(' ')
  end
   private

  def assign_lists
    if @list_titles
  self.lists = @list_titles.split(/\,/).map do |title|
    if title[0..0]==" "
      title=title.strip
    end
    title=title.downcase
    List.find_or_create_by_title(title)
   end
  end
 end

  def has_lists?
     errors.add(:base, 'This item needs to be assigned to a list before it can be saved.') if self.lists.blank?
   end

grouping.rb模型

 belongs_to :item
 belongs_to :list

 accepts_nested_attributes_for :item, :list

列表形式

 <%= form_with(model: list,  local: true) do |f| %>
<% if list.errors.any? %>
<div id="error_explanation">
  <h2><%= pluralize(list.errors.count, "error") %> prohibited this list from being saved:</h2>

  <ul>
  <% list.errors.full_messages.each do |message| %>
    <li><%= message %></li>
  <% end %>
  </ul>
</div>
<% end %>

<div class="field">
<%= f.label :title %>
<%= f.text_field :title, id: :list_title %>
</div>

<div>
<p><strong>Items:</strong></p>

 <%= f.fields_for :items do |item| %>
  <div>
    <%= item.label :title %>
    <%= item.text_field :title %>

    <%= item.label :url %>
    <%= item.text_field :url %>
  </div>
 <% end %>
 </div>




 <div class="actions">
<%= f.submit %>
 </div>
 <% end %>

控制台输出示例

于2017-09-19 13:12:53-0700开始POST“/lists”127.0.0.1由ListsController#创建为HTML参数：｛“utf8”=

很明显，我还在学习中——但是在尝试了这个论坛上所有相关的提示之后，我还是没有找到这个。感谢任何帮助！

Answer 1

当你定义你的参数时，你的语法有一些错误。应该是这样的:(items代替item并且你不需要{})

def list_params
  params.require(:list).permit(:title,
  items_attributes: [:id, :title, :url])
end

Answer 2

您快到了，但控制台日志中报告了一个错误：Unpermitted parameter:：items_attributes。

将item_attributes更改为items_attributeslist_params：

def list_params
  params.require(:list)
        .permit(:title, items_attributes: [:id, :title, :url])
end