Nested Form in Rails: questions answers - ruby-on-rails

Question

I have a problem with my rails application.
My models:
quiz: name
question: text, quiz_id
answer: text, question_id
right_answer: question_id, answer_id
A quiz has many questions. A single questions has many answers and a answer has only one right answer.
How can I solve this problem?
This is my form:
<%= form_for([#quiz, #question]) do |f| %>
<% if #question.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(#question.errors.count, "error") %> prohibited this question from being saved:</h2>
<ul>
<% #question.errors.full_messages.each do |message| %>
<li><%= message %></li>
<% end %>
</ul>
</div>
<% end %>
<div class="field">
<%= f.label :text %><br>
<%= f.text_field :text %>
</div>
<%= f.fields_for :answers do |u| %>
<%= u.text_field :text, class: "form-control", id: "answer"%>
<% end %>
<div class="actions">
<%= f.submit %>
I want to add a radio box to each answer to select which answer is the right.
Questions-Controller:
def new
#question = Question.new
#question.answers.build
end
def create
#question = Question.new(question_params)
#question.quiz_id = #quiz.id
i = 0
until question_params[:answers_attributes].count
#answer = #question.answers.new(question_params[:answers_attributes]["#{i}"])
#answer.save
i += 1
end
respond_to do |format|
if #question.save
format.html { redirect_to quiz_questions_path(#quiz), notice: 'Question was successfully created.' }
format.json { render :show, status: :created, location: #question }
else
format.html { render :new }
format.json { render json: #question.errors, status: :unprocessable_entity }
end
end
end
How can I do this in my Controller and in my form, because I only have one right_answer but I need 4 radio buttons in my form?
Thanks

Answer 1

= f.collection_radio_buttons :answer_id, #question.answers.all, :id, :name_with_initial

Answer 2

Add a new boolean field correct_answer in your answers table :
rails g migration add_correct_answer_to_answer correct_answer:boolean
questions_controller.rb
def new
#question = Question.new
4.times { #question.answers.build } # you can do it dynamically
end
def question_params
params.require(:question).permit(:text, answers_attributes: [:id, :text, :correct_answer])
end
questions/_form.rb
<%= f.fields_for :answers do |builder| %>
<%= render 'answer', f: builder %>
<% end %>
questions/_answer.html.erb
<%= f.label :text, "Answer" %>
<%= f.text_field :text %>
<%= f.radio_button :correct_answer %>
Then you can create a scope in question model to get correct answer of a particular question easily.