ruby-on-rails - 在 Rails 4 论坛应用程序中创建嵌套模型

Question

您好，我正在 Rails 4 中制作一个论坛应用程序。它可以有许多论坛，每个论坛都有许多主题。每个主题可以有多个帖子。创建新主题时，还必须创建初始帖子，就像 Stack Overflow 本身一样。因此，我在“新主题”表单中有一个文本区域，允许使用 fields_for方法。 问题是 , 当您在填写表单(包括“发布”字段)后单击“创建主题”按钮时，事务将被回滚。出现以下验证错误:

3 errors prohibited this topic from being saved:

• Posts forum must exist
• Posts topic must exist
• Posts user must exist

这是我的表格: app/views/topics/_form.html.erb

<%= form_for([ @forum, topic ]) do |f| %>
  <% if topic.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(topic.errors.count, "error") %> prohibited this topic from being saved:</h2>

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

  <div class="field">
    <%= f.label :title %><br>
    <%= f.text_field :title %>
  </div>

  <div class="field">
    <%= f.fields_for :posts do |builder| %>
      <%= builder.label :content %><br>
      <%= builder.cktext_area :content, class: 'ckeditor' %>
    <% end %>
  </div>

  <div class="actions">   
    <%= f.submit 'Create Topic', class: "btn btn-l btn-success" %>
  </div>
<% end %>

型号: 论坛.rb

class Forum < ApplicationRecord
    has_many :topics, dependent: :destroy
    has_many :posts, through: :topics

    def most_recent_post
      topic = Topic.last
      return topic
    end
end

topic.rb

class Topic < ApplicationRecord
  belongs_to :forum
  belongs_to :user

  has_many :posts, dependent: :destroy
  accepts_nested_attributes_for :posts

end

post.rb

class Post < ApplicationRecord
  belongs_to :forum
  belongs_to :topic
  belongs_to :user

  validates :content, presence: true
end

主题 Controller ， 应用程序/ Controller /topics_controller.rb

class TopicsController < ApplicationController
  before_action :get_forum
  before_action :set_topic, only: [:show, :edit, :update, :destroy]

  # GET /topics
  # GET /topics.json
  def index
    @topics = @forum.topics
  end

  # GET /topics/1
  # GET /topics/1.json
  def show
  end

  # GET /topics/new
  def new
    @topic = @forum.topics.build
    @topic.posts.build
  end

  # GET /topics/1/edit
  def edit
    # @topic.posts.build
  end

  # POST /topics
  # POST /topics.json
  def create
    @topic = @forum.topics.build(topic_params.merge(user_id: current_user.id))
    @topic.last_poster_id = @topic.user_id

    respond_to do |format|
      if @topic.save
        format.html { redirect_to forum_topic_path(@forum, @topic), notice: 'Topic was successfully created.' }
        format.json { render :show, status: :created, location: @topic }
      else
        format.html { render :new }
        format.json { render json: @topic.errors, status: :unprocessable_entity }
      end
    end
  end

  # PATCH/PUT /topics/1
  # PATCH/PUT /topics/1.json
  def update
    respond_to do |format|
      if @topic.update(topic_params)
        format.html { redirect_to forum_topic_path(@forum, @topic), notice: 'Topic was successfully updated.' }
        format.json { render :show, status: :ok, location: @topic }
      else
        format.html { render :edit }
        format.json { render json: @topic.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /topics/1
  # DELETE /topics/1.json
  def destroy
    @topic.destroy
    respond_to do |format|
      format.html { redirect_to forum_path(@forum), notice: 'Topic was successfully destroyed.' }
      format.json { head :no_content }
    end
  end

  private
    # Use callbacks to share common setup or constraints between actions.
    def get_forum
      @forum = Forum.find(params[:forum_id])
    end

    def set_topic
      @topic = Topic.find(params[:id])
    end

    # Never trust parameters from the scary internet, only allow the white list through.
    def topic_params
      params.require(:topic).permit(:title, :last_poster_id, :last_post_at, :tags, :forum_id, :user_id, posts_attributes: [:id, :content])
    end
end

如您所见，我添加了 posts_attributes到 的强参数话题 .这些是唯一的字段 帖子 除了外键引用( :forum_id, :topic_id, :user_id )。我试过把这些属性放进去，但我得到了同样的错误。

最后，这是我的 路线.rb

Rails.application.routes.draw do

  resources :forums do
    resources :topics do
      resources :posts
    end
  end
  resources :sessions
  resources :users
  mount Ckeditor::Engine => '/ckeditor'
end

我还应该提到我已经尝试添加 hidden_fields内部 fields_for , 与 id @forum、@topic 和 current_user 的标准。这会引发相同的验证错误。

我错过了什么？我觉得这是 Controller 中的东西。就像我没有正确保存它。我见过的每个教程都是这样的。除了 Rails <=3 版本，由于没有 strong_params，它们的方式不同。

有任何想法吗？谢谢您的帮助!

编辑 这是我尝试提交标题为“我是标题”的主题和内容“我是一些内容”时的日志输出...

Started POST "/forums/1/topics" for 127.0.0.1 at 2016-01-31 09:03:33 -0500
Processing by TopicsController#create as HTML
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"pYt842XQHiOKqNjPHBO8lNP2z92gHF7Lpt24CppbuvHR/cFHky3FVCpBs77p7WFRKmYBHgeZQjx0sE+DI+Q+sQ==", "topic"=>{"title"=>"I am a title", "posts_attributes"=>{"0"=>{"content"=>"<p>I am some content</p>\r\n"}}}, "commit"=>"Create Topic", "forum_id"=>"1"}
  Forum Load (0.6ms)  SELECT  "forums".* FROM "forums" WHERE "forums"."id" = $1 LIMIT $2  [["id", 1], ["LIMIT", 1]]
  User Load (0.6ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = $1 LIMIT $2  [["id", 1], ["LIMIT", 1]]
   (0.3ms)  BEGIN
  CACHE (0.0ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = $1 LIMIT $2  [["id", 1], ["LIMIT", 1]]
   (0.4ms)  ROLLBACK

Answer 1

这不是一个直接的答案；评论太长了。

您遇到的问题之一 routes是你nesting too many resources :

Resources should never be nested more than 1 level deep...

resources :x do
  resources :y
end

——

虽然你可以做你正在做的事情，但最好使用 scope :

#config/routes.rb
scope ':forum' do
   resources :topics do
      resources :posts
   end
end

您面临的问题是事情会变得非常复杂，非常快。虽然

这样，您可以制作 forums CRUD 可在其自己的一组功能中访问:

#config/routes.rb
resources :forums #-> only accessible to admins?
scope ...

无论哪种方式，您仍然需要使用 forum 定义您的路线。展示:

<%= link_to "Test", [@forum, @topic, @post] %>