Rails Has_Many :Through confusion - ruby-on-rails

Question

I'm working on creating a basic survey app as I'm learning rails. I've setup a has_many through relationship between the surveys as the questions (as questions may be used in multiple surveys). I've been struggling with adding a question to a survey though. Any idea what I need to do to create a new surveytization when creating my new question (and thus adding the question to the survey)? I'm able to do it in the console but am struggling with translating that to the controllers/views/params - if you know of any good documentation about those I'd love to check them out to (but thus far haven't found much).
It seems to error out when I try to assign my #survey variable using the :survey_id in the params I'm sending to the Question controller.
I really appreciate your help!
Question.rb:
class Question < ActiveRecord::Base
has_many :answers, dependent: :delete_all
validates :title, presence: true
has_many :surveytizations
has_many :surveys, :through => :surveytizations
end
Survey.rb
class Survey < ActiveRecord::Base
has_many :surveytizations
has_many :questions, :through => :surveytizations
end
Surveytization.rb:
class Surveytization < ActiveRecord::Base
has_many :surveys
has_many :questions
validates :survey_id, presence: true
validates :question_id, presence:true
end
SurveyController.rb:
class SurveysController < ApplicationController
before_action :set_survey, only: [:show, :edit, :update, :destroy]
before_action :set_question
# 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 action: 'show', status: :created, location: #survey }
else
format.html { render action: '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 { head :no_content }
else
format.html { render action: '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 }
format.json { head :no_content }
end
end
def add_question(question)
surveytizations.create!(question_id: question.id)
end
def remove_question(question)
surveytizations.find_by(question_id: question.id).destroy
end
def find_question(question)
#question = surveytizations.find_by(question_id: question.id)
end
private
# Use callbacks to share common setup or constraints between actions.
def set_survey
#survey = Survey.find(params[:id])
end
def set_question
#question = Question.new
end
# Never trust parameters from the scary internet, only allow the white list through.
def survey_params
params.require(:survey).permit(:title)
end
end
Survey show.html.erb:
<p id="notice"><%= notice %></p>
<p>
<strong>Title:</strong>
<%= #survey.title %>
</p>
<%= link_to 'Edit', edit_survey_path(#survey) %> |
<%= link_to 'Back', surveys_path %>
<%= link_to "Add Question", new_question_path(:survey_id => #survey.id)%>
QuestionController:
class QuestionsController < ApplicationController
before_action :set_question, only: [:show, :edit, :update, :destroy]
# GET /questions
# GET /questions.json
def index
#questions = Question.all
end
# GET /questions/1
# GET /questions/1.json
def show
#answers = #question.answers
end
# GET /questions/new
def new
#question = Question.new
#survey = Survey.find(:survey_id)
end
# GET /questions/1/edit
def edit
end
# POST /questions
# POST /questions.json
def create
#question = Question.new(question_params)
respond_to do |format|
if #question.save
format.html { redirect_to #question, notice: 'Question was successfully created.' }
format.json { render action: 'show', status: :created, location: #question }
else
format.html { render action: 'new' }
format.json { render json: #question.errors, status: :unprocessable_entity }
end
end
end
# PATCH/PUT /questions/1
# PATCH/PUT /questions/1.json
def update
respond_to do |format|
if #question.update(question_params)
format.html { redirect_to #question, notice: 'Question was successfully updated.' }
format.json { head :no_content }
else
format.html { render action: 'edit' }
format.json { render json: #question.errors, status: :unprocessable_entity }
end
end
end
# DELETE /questions/1
# DELETE /questions/1.json
def destroy
#question.destroy
respond_to do |format|
format.html { redirect_to questions_url }
format.json { head :no_content }
end
end
private
# Use callbacks to share common setup or constraints between actions.
def set_question
#question = Question.find(params[:id])
end
# Never trust parameters from the scary internet, only allow the white list through.
def question_params
params.require(:question).permit(:title, :single_response, :surveytization)
end
end

Answer 1

One problem is your join relation should have belongs_to instead of has_many, to get the has_many through working:
class Surveytization < ActiveRecord::Base
belongs_to :survey
belongs_to :question
validates :survey_id, presence: true
validates :question_id, presence:true
end
Notice the :survey and :question are singular name in the belongs_to
To Add a question to a survey you can
# create new question or find existing question and store it in #question
#question
# get the survey into #survey
#survey
#survey.questions << #question
This will magically create the surveytization as well. Now that question will belong to that survey.
You Don't even have to call #survey.save! after.