Rails嵌套窗體錯誤：param丟失或值爲空

Question

我在構建一個允許用戶創建比賽的應用程序。每場比賽都有很多問題，每場比賽都有很多條目。每個條目都有很多答案，每個問題都有很多答案。以下是我的型號：

class Answer < ActiveRecord::Base 
    belongs_to :entry 
    belongs_to :question 
end 

class Contest < ActiveRecord::Base 
    has_many :entries 
    has_many :questions 
end 

class Entry < ActiveRecord::Base 
    belongs_to :contest 
    has_many :answers 
    accepts_nested_attributes_for :answers, allow_destroy: true 
end 

class Question < ActiveRecord::Base 
    has_many :answers 
    belongs_to :contest 
end 

除了當我嘗試創建條目時，所有東西都可以使用。我得到一個「參數丟失或值是空的：輸入」錯誤。這裏是我的控制器：

class EntriesController < ApplicationController 
    before_action :set_entry, only: [:show, :edit, :update, :destroy] 
    before_action :set_contest 

    # GET /entries 
    # GET /entries.json 
    def index 
    @entries = Entry.all 
    end 

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

    # GET /entries/new 
    def new 
    @entry = Entry.new 
    end 

    # GET /entries/1/edit 
    def edit 
    end 

    # POST /entries 
    # POST /entries.json 
    def create 
    @entry = Entry.new(entry_params) 
    @entry.contest = @contest 
    respond_to do |format| 
     if @entry.save 
     format.html { redirect_to @entry, notice: 'Entry was successfully created.' } 
     format.json { render :show, status: :created, location: @entry } 
     else 
     format.html { render :new } 
     format.json { render json: @entry.errors, status: :unprocessable_entity } 
     end 
    end 
    end 

    # PATCH/PUT /entries/1 
    # PATCH/PUT /entries/1.json 
    def update 
    respond_to do |format| 
     if @entry.update(entry_params) 
     format.html { redirect_to @entry, notice: 'Entry was successfully updated.' } 
     format.json { render :show, status: :ok, location: @entry } 
     else 
     format.html { render :edit } 
     format.json { render json: @entry.errors, status: :unprocessable_entity } 
     end 
    end 
    end 

    # DELETE /entries/1 
    # DELETE /entries/1.json 
    def destroy 
    @entry.destroy 
    respond_to do |format| 
     format.html { redirect_to entries_url, notice: 'Entry was successfully destroyed.' } 
     format.json { head :no_content } 
    end 
    end 

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

    def set_contest 
     @contest = Contest.find(params[:contest_id]) 
    end 

    # Never trust parameters from the scary internet, only allow the white list through. 
    def entry_params 
     params.require(:entry).permit(:contest_id, answers_attributes: [:id, :content, :entry_id, :question_id, :_destroy]) 
    end 
end 

這裏是我的參賽表格：

<%= simple_form_for([@contest, @entry]) do |f| %> 
    <%= f.error_notification %> 

    <div class="form-inputs"> 
    <h3>Questions</h3> 
    <%= simple_fields_for :answers do |ff| %> 
     <% @contest.questions.each do |question| %> 
      <h4><%= question.content %></h4> 
      <%= ff.input :content, input_html: {class: 'form-control'} %> 
     <% end %> 
    <% end %> 
    </div> 

    <div class="form-actions"> 
    <%= f.button :submit %> 
    </div> 
<% end %> 

我還在工作的邏輯，但很困惑，爲什麼報名表給我這個錯誤。任何幫助，將不勝感激！

UPDATE

在Rails的指南例如他們表現出新的行動：

def new 
    @person = Person.new 
    2.times { @person.addresses.build} 
end 

我需要建立在我的新行動的答案對象？我不確定...我嘗試過，但沒有奏效。我覺得這不可能是問題，但作爲錯誤從entry_params方法

Answer 1

你應該加入這行來你new行動。

@entry.answers.build 

而改變這一行

<%= simple_fields_for :answers do |ff| %> 

到

<%= f.simple_fields_for :answers do |ff| %>