product-models.py

class Product(models.Model):
    name = models.CharField(max_length=256, unique=True)

    def __unicode__(self):
        return self.name

class Topic(models.Model):
    name = models.CharField(max_length=256)
    product = models.ForeignKey('Product', related_name='topics')

    class Meta:
        unique_together = ("name", "product")

    def __unicode__(self):
        return self.name

class Module(models.Model):
    name = models.CharField(max_length=256, unique=True)
    threshold = models.IntegerField()
    topic = models.ForeignKey('Topic', related_name='modules')

    def __unicode__(self):
        return self.name

class Choice(models.Model):
    question = models.ForeignKey('Question', related_name='choices')
    choice = models.CharField(max_length=255)
    order = models.IntegerField(default=0)
    count = models.IntegerField(default=0, editable=False)
    is_correct = models.BooleanField(default=False)

    def __unicode__(self):
        return self.choice

#multiple choice question
class Question(models.Model):
    quiz = models.ForeignKey('Quiz', related_name='questions')
    question = models.CharField(max_length=64)
    
    module = models.ForeignKey('Module', related_name='questions')

    times_correct = models.IntegerField(editable=False, default=0)
    times_total = models.IntegerField(editable=False, default=0)

    def _get_average(self):
        "Returns the average in percent"
        if self.times_total != 0:
            return (self.times_correct / float(self.times_total))*100
        return 0.0
    average = property(_get_average)

    def __unicode__(self):
        return self.question

class Quiz(models.Model):
    #id = models.UUIDField(primary_key=True)
    name = models.CharField(max_length=64)
    #questions = models.ManyToManyField(Question)
    created_by = models.ForeignKey(settings.AUTH_USER_MODEL, related_name="quizzes")

    #questions = models.ManyToManyField(QuestionManager, null=True, related_name="quiz")

    class Meta:
        verbose_name_plural = "quizzes"

    def __unicode__(self):
        return self.name