Nested Form in Rails 4 not being rendered in view - ruby-on-rails

Question

Apologies if this has already been answered but I can't find anything that can help me. I am a newbie with Rails so please be gentle :D
I have been pulling my hair out trying to get nested forms working, I am sure I got nested forms working using Rails 3 and the railscasts demo last year, but Rails 4 is beating me.
Looking at the log, the query is being run to pull the data for the associated table, but nothing is rendered in the form.
I have read many web sites, but none have helped so far and I don't know where to start. The latest article I have followed is this http://www.createdbypete.com/articles/working-with-nested-forms-and-a-many-to-many-association-in-rails-4/
Still nothing being rendered in the view.
Where do I start debugging this, maybe my Rails install is broken?? But I am probably missing something crucial.
Thanks,
Royce
Edit - I have added some of the controllers and the view in question
surveys_controller.rb
class SurveysController < ApplicationController
before_action :set_survey, only: [:show, :edit, :update, :destroy, :answers]
# 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
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
def answers
#participants = Participant.all
#questions = #survey.questions
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,
:questions_attributes => [:id, :content,
:answers_attributes => [:id, :content, :participant_id]
])
end
end
participents_controller.rb
class ParticipantsController < ApplicationController
before_action :set_participant, only: [:show, :edit, :update, :destroy]
# GET /participants
# GET /participants.json
def index
#participants = Participant.all
end
# GET /participants/1
# GET /participants/1.json
def show
end
# GET /participants/new
def new
#participant = Participant.new
end
# GET /participants/1/edit
def edit
end
# POST /participants
# POST /participants.json
def create
#participant = Participant.new(participant_params)
respond_to do |format|
if #participant.save
format.html { redirect_to #participant, notice: 'Participant was successfully created.' }
format.json { render :show, status: :created, location: #participant }
else
format.html { render :new }
format.json { render json: #participant.errors, status: :unprocessable_entity }
end
end
end
# PATCH/PUT /participants/1
# PATCH/PUT /participants/1.json
def update
respond_to do |format|
if #participant.update(participant_params)
format.html { redirect_to #participant, notice: 'Participant was successfully updated.' }
format.json { render :show, status: :ok, location: #participant }
else
format.html { render :edit }
format.json { render json: #participant.errors, status: :unprocessable_entity }
end
end
end
# DELETE /participants/1
# DELETE /participants/1.json
def destroy
#participant.destroy
respond_to do |format|
format.html { redirect_to participants_url, notice: 'Participant was successfully destroyed.' }
format.json { head :no_content }
end
end
private
# Use callbacks to share common setup or constraints between actions.
def set_participant
#participant = Participant.find(params[:id])
end
# Never trust parameters from the scary internet, only allow the white list through.
def participant_params
params.require(:participant).permit(:name)
end
end
application_controller.rb
class ApplicationController < ActionController::Base
# Prevent CSRF attacks by raising an exception.
# For APIs, you may want to use :null_session instead.
protect_from_forgery with: :exception
end
answers.html.erb
<h1><%= #survey.name %> Answers</h1>
<%= form_for(#survey) do |f| %>
<% #participants.each do |participant| -%>
<h3><%= participant.name %></h3>
<table>
<thead>
<tr>
<td>Questions</td>
<td>Answer</td>
</tr>
</thead>
<tbody>
<% #questions.each do |question| -%>
<tr>
<td><%= question.content %></td>
<td>
<%= f.fields_for :questions, question do |q| -%>
<%= q.fields_for :answers, question.answers.find_or_initialize_by(participant: participant) do |a| -%>
<%= a.text_area :content %>
<%= a.hidden_field :participant_id, participant.id %>
<% end -%>
<% end -%>
</td>
</tr>
<% end -%>
</tbody>
</table>
<% end -%>
<div class="actions">
<%= f.submit %>
</div>
<% end -%>

Answer 1

As you're new with Rails, let me explain how nested forms work for you!
--
Nested
Nested forms are not actually nested at all - they are associative forms.
You must remember that Rails (by virtue of being built on Ruby) is an object orientated framework. OOP (object orientated programming) is not just a buzzword - it's a fundamental core construction for your application & how it hands input / execution.
The problem many people have is they don't realize the true nature of Rails, and consequently become confused about how its many features work. If you appreciate that everything you do in Rails should be constructed around objects, life gets much simpler!
--
Form
With this in mind, you can begin to appreciate the role of objects throughout Rails, to the degree that you need to build / invoke objects for every element of your Rails application, including your form:
#app/models/survey.rb
Class Survey < ActiveRecord::Base
has_many :questions
accepts_nested_attributes_for :questions
end
#app/controllers/surveys_controller.rb
Class SurveysController < ApplicationController
def new
#survey = Survey.new
#survey.questions.build #-> very important
end
end
#app/views/surveys/new.html.erb
<%= form_for #survey do |f| %>
...
<%= f.fields_for :questions do |q| %>
<%= q.text_field :title %>
<% end %>
<%= f.submit %>
<% end %>
This should create a form which allows you to pass associative data through to your child model. There are several important elements to consider:
You need to include accepts_nested_attributes_for in your "parent" model
You need to build your associative objects
You need to populate your form with the relative objects
By following this simple pattern, you'll be able to populate the nested form that you wish to show in the view

Answer 2

Try to use the following code:
<%= f.fields_for :questions do |q| -%>
<%= q.fields_for :answers, q.object.answers.find_or_initialize_by(participant: f.object.participant) do |a| -%>
<%= a.text_area :content %>
<%= a.hidden_field :participant_id, participant.id %>
<% end -%>
<% end -%>
and make sure that you render to answers.html.erb, you have accepts_nested_attributes_for :questions in survey.rb file, and accepts_nested_attributes_for :answers in question.rb file

Answer 3

Have you got accepts_nested_attributes_for :question in your survey model? And the same for the answer model?