To start your Phoenix server:

• Install dependencies with mix deps.get
• Create and migrate your database with mix ecto.setup
• Install Node.js dependencies with cd assets && npm install
• Start Phoenix endpoint with mix phx.server

Now you can visit localhost:4000 from your browser.

This app is deployed to https://twentyquiz.gigalixirapp.com and can be tested there.

Here are tables I created for this app.

users

• name

quizzes: has_many questions

• title
• description
• image_url

questions: has_many choices, belongs_to quiz

• text
• quiz_id

choices: belongs_to question

• text
• question_id

answers: belongs_to user, belongs_to choice

• choice_id
• user_id

The app is called Survey and has two contexts.

• Accounts which just has one User schema.
• Questionnaire which consists of the Quiz, Question, Choice and Answer schemas

The Accounts api is in lib/survey/accounts.ex Questionnaire api is in lib/survey/questionnaire.ex

The schemas for the contexts are in lib/survey/accounts and lib/survey/questionnaire

The main controllers are lib/survey_web/controllers/user_controller.ex and lib/survey_web/controllers/quiz_controller.ex

The controllers take params if any and call the Accounts and Questionnaire context apis to do the work.

The main view templates are lib/survey_web/templates/user and quiz

The home page is consists of a simple login where you're presented with a list of existing users and click on one to log in or you can create a new user.

After logging in, you're redirected to the quiz listing page. This will list the quizzes the current user has not yet completed. The database is seeded with two quizzes with two questions for each quiz.

The controller action for the quiz listing page is lib/survey_web/controllers/quiz_controller.ex#index

Questionnaire.list_not_completed_quizzes_for_user/1 calls a query to figure out which quizzes are unfinished for the current user. That query is in lib/survey/questionair/quiz.ex#not_completed_for/2. Those quizzes are listed in the quiz listing page.

Once you click on a quiz, you're forwarded to a start page. When you click the start link, you're directed to quiz_controller.ex#next_question. This calls the Question.next_unanswered_question_for/3 query in lib/survey/questionnaire/question.ex to grab the next unanswered question for this quiz and user.

Then you cycle through the two questions and submit answers which are saved to the DB. Once you get the the last page, you can click to go back to the home quiz listing page and the quiz you just completed will not be there anymore.

Here's some SQL to display all the answers aligned with the question, quiz, and user.

SELECT
  users.name AS user,
  quizzes.title AS quiz,
  questions.text AS question,
  choices.text AS answer
FROM
  quizzes
JOIN questions ON questions.quiz_id = quizzes.id
JOIN choices ON choices.question_id = questions.id
JOIN answers ON answers.choice_id = choices.id
JOIN users ON answers.user_id = users.id