Rails 4 - Nested form with accepts_nested_attributes_for controller setup?

问题

I'm trying to make a nested form with form_for and fields_for. After much research and in-success, not working on my project anymore. I'm just trying to recreate a railscast to see what have I done wrong.

I'm trying to re-create the example found at http://railscasts.com/episodes/196-nested-model-form-part-1 which shouldn't be that hard since the code is there, but I can't manage to create questions from the survey. Here is my code until now:

rails new surveysays
rails g scaffold survey name:string
rake db:migrate
rails g scaffold question survey_id:integer content:text
rake db:migrate

I'm trying to do in the exact same sequence of the video. My Question model:

class Question < ActiveRecord::Base
  belongs_to :survey
end

My Survey model:

class Survey < ActiveRecord::Base
  has_many :questions, dependent: :destroy
  accepts_nested_attributes_for :questions
end

My survey form with nested questions fields:

<%= form_for(@survey) do |f| %>
      ...
      <div class="field">
        <%= f.label :name %><br>
        <%= f.text_field :name %>
      </div>
      <%= f.fields_for :questions do |builder| %>
        <p>
          <%= builder.label :content, "Question" %><br/>
          <%= builder.text_area :content, :row => 3 %>
        </p>
      <% end %>
      <div class="actions">
        <%= f.submit %>
      </div>
   <% end %>

My survey show:

<p id="notice"><%= notice %></p>

<p>
  <strong>Name:</strong>
  <%= @survey.name %>
</p>

<ol>
  <% for question in @survey.questions %>
   <li><%=h question.content%></li>
  <% end %>
</ol>

<%= link_to 'Edit', edit_survey_path(@survey) %> |
<%= link_to 'Back', surveys_path %>

And my SurveysController:

class SurveysController < ApplicationController
 ...

  # GET /surveys/new
  def new
    @survey = Survey.new
    3.times { @survey.questions.build }
  end

 ...

  # POST /surveys
  # POST /surveys.json
  def create
    @survey = Survey.new(survey_params)

    respond_to do |format|
      if @survey.save
        format.html { redirect_to @survey, notice: 'Survey was successfully created.' }
        format.json { render :show, status: :created, location: @survey }
      else
        format.html { render :new }
        format.json { render json: @survey.errors, status: :unprocessable_entity }
      end
    end
  end

  ...

  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)
    end
end

As until min 5:34 and thats when it doesn't work as shown in the video and doesn't create the questions, the form appears with the 3 questions, I fill the form, but when a press create it doesn't create the questions:

Loading development environment (Rails 4.1.6) 2.1.3 :001 > s = Survey.all Survey Load (3.0ms) SELECT "surveys".* FROM "surveys" => #]> 2.1.3 :002 > q = s[0].questions Question Load (0.6ms) SELECT "questions".* FROM "questions" WHERE "questions"."survey_id" = ? [["survey_id", 2]] => #

I can't see any difference between my code and the example. I even tried to make some alterations in the SurveysController without any success:

Inserting question_attributes:[:id ,:content] in permit of method survey_params or Inserting @survey.questions.create(survey_params[:questions_attributes]) after if survey.save on create method, this creates the question but with content: nill

At this point I am stuck. I don't know what more what to do, what am I missing int the controller? Can anyone give me some help, thanks.

回答1:

On the survey_params method in the controller, you are missing the question params, it should look like:

def survey_params
 params.require(:survey).permit(:name, :questions_attributes => [:question, :answer ... or whatever attribute for the question model])
end

Let me know how it goes!

回答2:

The survey_params needs to change to permit the nested attributes, from:

def survey_params
   params.require(:survey).permit(:name)
end

to:

def survey_params
  params.require(:survey).permit(:name, questions_attributes: [:id , :content])
end

来源：https://stackoverflow.com/questions/27682951/rails-4-nested-form-with-accepts-nested-attributes-for-controller-setup

标签

ruby-on-rails-4

controller

nested-forms

nested-attributes