Rails - Simple Form - Nested Resources paths - ruby-on-rails

Question

I am trying to make an app in Rails 4 using simple form.
I have 3 models: Project, Project_Question, Project_Answer
The associations are:
Project:
has_many :project_questions, dependent: :destroy#, through: :projects
accepts_nested_attributes_for :project_questions
Project Question:
belongs_to :project#, counter_cache: true
has_one :project_answer, dependent: :destroy
belongs_to :user
accepts_nested_attributes_for :project_answer
Project Answer:
belongs_to :project_question#, counter_cache: true
belongs_to :user
My routes are nested as follows:
resources :projects do
resources :project_questions do
resources :project_answers
end
end
In my Project Questions partial, I want a link to answer the question. I have a link that is set out as follows:
<%= link_to 'Answer this question', new_project_project_question_project_answer_path(:project_id => #project.id, :project_question_id => singleQuestion.id) %>
I got help getting to the link point with help on the attached question:
http://stackoverflow.com/questions/30978447/rails-link-to-path
I since changed the project answer model so that project question has one (rather than has many project answers) and updated the path in the Answer this Question link, to singular instead of plural.
When I click the 'Answer this question' link, I get this error:
undefined method `project_answers_path'
It is pointing to the simple form for line in the project answers form. That form has:
<%= simple_form_for [#project, #project_question, #project_answer] do |f| %>
<%= f.input :project_question_id, as: :hidden, input_html: {value: #project_question.id} %>
<%= f.input :answer, label: 'Answer?', :label_html => {:class => 'question-project'}, placeholder: 'Type your answer here', :input_html => {:style => 'width: 650px', class: 'response-project'} %>
<br><br><br>
<%= f.button :submit, 'Send!', :class => "cpb" %>
<% end %>
When I rake routes for project answer, I get:
project_project_question_project_answers GET /projects/:project_id/project_questions/:project_question_id/project_answers(.:format) project_answers#index
POST /projects/:project_id/project_questions/:project_question_id/project_answers(.:format) project_answers#create
new_project_project_question_project_answer GET /projects/:project_id/project_questions/:project_question_id/project_answers/new(.:format) project_answers#new
edit_project_project_question_project_answer GET /projects/:project_id/project_questions/:project_question_id/project_answers/:id/edit(.:format) project_answers#edit
project_project_question_project_answer GET /projects/:project_id/project_questions/:project_question_id/project_answers/:id(.:format) project_answers#show
PATCH /projects/:project_id/project_questions/:project_question_id/project_answers/:id(.:format) project_answers#update
PUT /projects/:project_id/project_questions/:project_question_id/project_answers/:id(.:format) project_answers#update
DELETE /projects/:project_id/project_questions/:project_question_id/project_answers/:id(.:format) project_answers#destroy
I don't understand why the #new action for the project_project_questions_project_answers action is plural for answers when there will only be one answer, but I think this has something to do with the error message I get when I click the 'Answer this Question' link.
new_project_project_question_project_answer GET /projects/:project_id/project_questions/:project_question_id/project_answers/new(.:format) project_answers#new
e
When I try pluralising the first line of the form for project answers, for project questions, like this:
<%= simple_form_for [#project, #project_questions, #project_answer] do |f| %>
I get this error:
undefined method `project_answers_path' for #<#<Class:0x0000010a193f10>:0x0000010a3abb40>
When I try pluralising the first line of the form for project answers, for project questions and project answers, like this:
<%= simple_form_for [#project, #project_questions, #project_answers] do |f| %>
I get this error:
undefined method `model_name' for NilClass:Class
Can anyone see what I've done wrong? I read a post suggesting that I use project_answer (singular) in the routes.rb. I tried this but I get an error saying no route matches the plural.
Project Answer Controller:
class ProjectAnswersController < ApplicationController
before_action :set_project_answer, only: [:show, :edit, :update, :destroy]
# GET /project_answers
# GET /project_answers.json
def index
#project_answers = ProjectAnswer.all
end
# GET /project_answers/1
# GET /project_answers/1.json
def show
end
# GET /project_answers/new
def new
#project_answer = ProjectAnswer.new
end
# GET /project_answers/1/edit
def edit
end
# POST /project_answers
# POST /project_answers.json
def create
#project_answer = ProjectAnswer.new(project_answer_params)
respond_to do |format|
if #project_answer.save
format.html { redirect_to #project_answer, notice: 'Project answer was successfully created.' }
format.json { render action: 'show', status: :created, location: #project_answer }
else
format.html { render action: 'new' }
format.json { render json: #project_answer.errors, status: :unprocessable_entity }
end
end
end
# PATCH/PUT /project_answers/1
# PATCH/PUT /project_answers/1.json
def update
respond_to do |format|
if #project_answer.update(project_answer_params)
format.html { redirect_to #project_answer, notice: 'Project answer was successfully updated.' }
format.json { head :no_content }
else
format.html { render action: 'edit' }
format.json { render json: #project_answer.errors, status: :unprocessable_entity }
end
end
end
# DELETE /project_answers/1
# DELETE /project_answers/1.json
def destroy
#project_answer.destroy
respond_to do |format|
format.html { redirect_to project_answers_url }
format.json { head :no_content }
end
end
private
# Use callbacks to share common setup or constraints between actions.
def set_project_answer
#project_answer = ProjectAnswer.find(params[:id])
end
# Never trust parameters from the scary internet, only allow the white list through.
def project_answer_params
params[:project_answer].permit(:answer, :project_question_id)
end
end

Answer 1

Your new action of project_answers controller should be having #project, #project_question defined
def new
#project_answer = ProjectAnswer.new
#project = Project.find(params[:project_id])
#project_question = ProjectQuestion.find(params[:project_question_id])
end
So that you can use those in the form like this
<%= simple_form_for [#project, #project_question, #project_answer] do |f| %>