编辑时，RoR嵌套属性会产生重复的内容 [英] RoR nested attributes produces duplicates when edit

问题描述

我试图跟随瑞恩·贝茨 RailsCast＃196：嵌套模型形成第1部分。 Ryans版本有两个明显的区别：1）我正在使用内置的脚手架，而不是漂亮，因为他正在使用，2）我正在运行rails 4（我不知道在他的演员中使用什么版本，但不是4）。

所以这里是我做的

  rails new survey2 
 cd survey2 
 bundle install 
 rails生成脚手架调查名称：string 
 rake db：migrate 
 rails生成模型问题survey_id：整数内容：text 
 rake db：migrate 
  

然后我将关联添加到这样的模型中

 类问题< ActiveRecord :: Base 
 belongs_to：survey 
 end 
  

等

 类调查< ActiveRecord :: Base 
 has_many：questions 
 acceptance_nested_attributes_for：questions 
 end 
  

然后我添加了嵌套视图部分

 <％= form_for（@survey）do | f | ％GT; 
<！ - 标准导轨4查看内容 - > 
 
< div class =field> 
<％= f.label：name％>< br> 
<％= f.text_field：name％> 
< / div> 
< div class =field> 
<％= f.fields_for：questions do | builder | ％GT; 
< div> 
<％= builder.label：content，问题％>< br /> 
<％= builder.text_area：content，：rows => 3％> 
< / div> 
<％end％> 
< / div> 
< div class =actions> 
<％= f.submit％> 
< / div> 
<％end％> 
  

最后控制器，以便每当新的调查被实例化时创建3个问题

  class SurveysController< ApplicationController 
 before_action：set_survey只有：[：show，：edit，：update，，destroy] 
 
＃标准rails 4索引并显示
 
＃GET /调查/新
 def new 
 @survey = Survey.new 
 3.times {@ survey.questions.build} 
 Rails.logger.debug（新方法执行） 
结束
 
＃GET /考察/ 1 /编辑
 def编辑
结束
 
＃标准轨道4创建
 
＃PATCH / PUT / survey / 1 
＃PATCH / PUT /surveys/1.json 
 def update 
 respond_to do | format | 
 if @ survey.update（survey_params）
 format.html {redirect_to @survey，notice：'Survey was successfully updated。'} 
 format.json {head：no_content} 
 else 
 format.html {render action：'edit'} 
 format.json {render json：@ survey.errors，status：：unprocessable_entity} 
 end 
 end 
 end 
 
＃标准rails 4 destroy 
 
 private 
＃使用回调来共享动作之间的通用设置或约束。 
 def set_survey 
 @survey = Survey.find（params [：id]）
 end 
 
＃从不信任来自可怕互联网的参数，只允许白名单通过。 
 def survey_params 
 params.require（：survey）.permit（：name，questions_attributes：[：content]）
 end 
 end 
  

所以，用三个问题创建一个新的调查是可以的。但是，如果我尝试编辑其中一个调查，原来的三个问题将得到维护，另外还有三个问题被创建。所以我现在已经有6个问题了，我现在已经有6个了。我添加了

  Rails.logger.debug方法执行）
  

到控制器中的新方法，据我所知，它当我进行编辑操作时不执行。任何人都可以告诉我我在做错什么？

非常感谢任何帮助！

解决方案

所以我想出来了。我必须在 survey_params 方法中将：id 添加到允许的参数中。现在看起来像这样：

 ＃不要信任来自可怕的互联网的参数，只允许白名单。 
 def survey_params 
 params.require（：survey）.permit（：name，questions_attributes：[：id，：content]）
 end 
  / pre> 
 
 
哪个工作完美。我是一个RoR新手，所以请用一点盐分对我的分析，但我猜，新的id的生成地点，而不是传递给更新动作。希望这有助于别人在那里。
 
I'm trying to follow Ryan Bates RailsCast #196: Nested model form part 1. There're two apparent differences to Ryans version: 1) I'm using built-in scaffolding and not nifty as he's using, and 2) I'm running rails 4 (I don't really know what version Ryans using in his cast, but it's not 4).

So here's what I did
rails new survey2
cd survey2
bundle install
rails generate scaffold survey name:string
rake db:migrate
rails generate model question survey_id:integer content:text
rake db:migrate
Then I added the associations to the models like so
class Question < ActiveRecord::Base
  belongs_to :survey
end
and so
class Survey < ActiveRecord::Base
  has_many :questions
  accepts_nested_attributes_for :questions
end
Then I added the nested view part
<%= form_for(@survey) do |f| %>
  <!-- Standard rails 4 view stuff -->

  <div class="field">
    <%= f.label :name %><br>
    <%= f.text_field :name %>
  </div>
  <div class="field">
    <%= f.fields_for :questions do |builder| %>
      <div>
        <%= builder.label :content, "Question" %><br/>
        <%= builder.text_area :content, :rows => 3 %>
      </div>
    <% end %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>
and finally the controller so that 3 questions are created whenever a new survey is instantiated
class SurveysController < ApplicationController
  before_action :set_survey, only: [:show, :edit, :update, :destroy]

  # Standard rails 4 index and show 

  # GET /surveys/new
  def new
    @survey = Survey.new
    3.times { @survey.questions.build }
    Rails.logger.debug("New method executed")
  end

  # GET /surveys/1/edit
  def edit
  end

  # Standard rails 4 create

  # PATCH/PUT /surveys/1
  # PATCH/PUT /surveys/1.json
  def update
    respond_to do |format|
      if @survey.update(survey_params)
        format.html { redirect_to @survey, notice: 'Survey was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render action: 'edit' }
        format.json { render json: @survey.errors, status: :unprocessable_entity }
      end
    end
  end

  # Standard rails 4 destroy

  private
    # Use callbacks to share common setup or constraints between actions.
    def set_survey
      @survey = Survey.find(params[:id])
    end

    # Never trust parameters from the scary internet, only allow the white list through.
    def survey_params
      params.require(:survey).permit(:name, questions_attributes: [:content])
    end
end
So, creating a new survey with three questions is fine. However, if I try to edit one of the surveys, the original three questions are maintained, while an additional three more are created. So instead of having 3 questions for the edited survey, I now have 6. I added
Rails.logger.debug("New method executed")
to the new method in the controller, and as far as I can tell, it is not executed when I'm doing an edit operation. Can anyone tell me what I'm doing wrong?

Any help is greatly appreciated!
解决方案
So I figured it out. I had to add :id to the permitted params in the survey_params method. It now looks like this:
# Never trust parameters from the scary internet, only allow the white list through.
def survey_params
  params.require(:survey).permit(:name, questions_attributes: [:id, :content])
end
which works perfectly. I'm a RoR newbie, so please take my analysis of this with a grain of salt, but I guess that new id's where generated instead of being passed to the update action. Hope this helps someone else out there.

                        
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