Rails Associations and db design for Quiz Application

Question

I am building this quiz application. I want it to be kinda sophisticated.

I have come up with this database schema. But I am really confused.. Confused about what a

Answer 1

Let's see, that would be:

# For Questions: 
:has_many => :answers
:belongs_to => :test_question
  # questions table should have the "test_question_id" column

# Answers:
:has_many => :candidate_answers
:belongs_to => :question 
  # Answers table should have the "question_id" column

#Test Questions:
:has_many => :questions
:has_many => :candidate_answers
:belongs_to => :test
  # test questions table should have the "test_id" column but not the "question_id"

#Tests: 
:has_many => :results
:has_many => :test_questions
:has_many => :candidates, :through => :results, :foreign_key => "candidate_id" #why not? ^^

#Results
:belongs_to => :test
:belongs_to => :candidate
  # Results table should have the "test_id" and "candidate_id" columns

#candidate_answers 
:belongs_to => :candidate
:belongs_to => :test_question
:belongs_to => :answer
  # candidate_answers table should have the "test_question_id", "candidate_id" and "answer_id" columns

#Candidates
:has_many => :candidate_answers
:has_many => :results
:has_many => :answered_tests, :class_name => "test", :through => :results, :foreign_key => "test_id" # again, why not?

And with the information you gave, that should do what you want. ;)

Answer 2

This should do:

• Drop candidate_answers.test_question
• Drop the candidate_answers table

• Drop the test_questions table

  class Test < ActiveRecord::Base has_many :results has_many :questions end

  class Result < ActiveRecord::Base belongs_to :test belongs_to :candidate end

  class Candidate < ActiveRecord::Base has_many :results has_many :answers end

  class Answer < ActiveRecord::Base belongs_to :question belongs_to :candidate end

  class Question < ActiveRecord::Base belongs_to :test has_many :answers end

It looks like you were intending to reuse the answers for more than one question, that would be a generally bad idea.. Better clone an answer in that case.