Nested forms, running into weird errors - ruby-on-rails

Question

I'm making a survey app, I've got 3 models: Survey, Question, and Answer. Survey has_many questions, Question has_many answers.
I've got two main errors:
My code is supposed to generate 4 answer fields for each question but only 1 answer field is generated.
When I press submit on my form, I get
unknown attribute 'answers' for Survey.
Extracted source (around line #33):
# POST /surveys.json
def create
#survey = Survey.new(survey_params)
respond_to do |format|
if #survey.save
I think the second problem is related to the answers model in some way but I'm not sure how. Here's my code:
surveys_controller:
class SurveysController < ApplicationController
before_action :set_survey, only: [:show, :edit, :update, :destroy]
# GET /surveys
# GET /surveys.json
def index
#surveys = Survey.all
end
# GET /surveys/1
# GET /surveys/1.json
def show
end
# GET /surveys/new
def new
#survey = Survey.new
3.times do
question = #survey.questions.build
4.times { question.answers.build }
end
end
# GET /surveys/1/edit
def edit
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
# 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 { render :show, status: :ok, location: #survey }
else
format.html { render :edit }
format.json { render json: #survey.errors, status: :unprocessable_entity }
end
end
end
# DELETE /surveys/1
# DELETE /surveys/1.json
def destroy
#survey.destroy
respond_to do |format|
format.html { redirect_to surveys_url, notice: 'Survey was successfully destroyed.' }
format.json { head :no_content }
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!
end
end
surveys/_form.html.erb
<%= form_for(#survey) do |f| %>
<% if #survey.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(#survey.errors.count, "error") %> prohibited this survey from being saved:</h2>
<ul>
<% #survey.errors.full_messages.each do |message| %>
<li><%= message %></li>
<% end %>
</ul>
</div>
<% end %>
<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, :rows => 3 %>
</p>
<%= f.fields_for :answers do |builder| %>
<p>
<%= builder.label :content, "Answer" %>
<%= builder.text_field :content %>
</p>
<% end %>
<% end %>
<div class="actions">
<%= f.submit %>
</div>
<% end %>
surveys/show.html.erb
<p id="notice"><%= notice %></p>
<p>
<strong>Name:</strong>
<%= #survey.name %>
</p>
<ol>
<% #survey.questions.each do |question| %>
<li><%= question.content %>
<ul>
<% for answer in question.answers %>
<li><%= answer.content %></li>
<% end %>
</ul>
</li>
<% end %>
</ol>
<%= link_to 'Edit', edit_survey_path(#survey) %> |
<%= link_to 'Back', surveys_path %>
survey.rb:
class Survey < ActiveRecord::Base
has_many :questions, :dependent => :destroy
accepts_nested_attributes_for :questions, :reject_if => -> (a) {a[:content].blank? }, :allow_destroy => true
end
question.rb:
class Question < ActiveRecord::Base
belongs_to :survey
has_many :answers, :dependent => :destroy
accepts_nested_attributes_for :answers, :reject_if => -> (a) {a[:content].blank? }, :allow_destroy => true
end
answer.rb
class Answer < ActiveRecord::Base
belongs_to :question
end
Any help would be appreciated, I've been stuck on this for hours now!

Answer 1

I don't know if the errors could be related to the fields_for, what happens when you do:
<%= f.fields_for :questions do |question_attribute| %>
<p>
<%= question_attribute.label :content, "Question" %><br />
<%= question_attribute.text_area :content, :rows => 3 %>
</p>
<%= question_attribute.fields_for :answers do |answer_attribute| %>
<p>
<%= answer_attribute.label :content, "Answer" %>
<%= answer_attribute.text_field :content %>
</p>
<% end %>
<% end %>
Let me know what is the outcome of that.