Django 过滤外查询键

Question

In this quiz game, I'm trying to filter the questions of a particular course.

models.py

class Course(models.Model):
    course_name = models.CharField(max_length=50)
    date_created = models.DateTimeField(auto_now_add=True)

class Quiz(models.Model):
    course_name = models.ForeignKey(Course, on_delete=models.CASCADE, related_name='quiz_course')
    question = models.TextField(max_length=100)

class Choice(models.Model):
    question = models.ForeignKey(Quiz, on_delete=models.CASCADE, related_name="choice_question")
    choice = models.CharField(max_length=100)
    is_true = models.BooleanField("This is Correct Answer", default=False)

class Quizgame(models.Model):
    user = models.OneToOneField(User, on_delete=models.CASCADE)
    total_score = models.DecimalField("Total score", default=0, decimal_places=2, max_digits=6)
    start_time = models.DateTimeField(auto_now_add=True)
    finish_time = models.DateTimeField(null=True)
    
    def get_new_question(self,course_id):
        used_question = AttemptedQuestion.objects.filter(quiz_profile=self).values_list('question__id',flat=True)
        remaining_questions = Quiz.objects.exclude(id__in=used_question)
        if not remaining_questions.exists():
            return
        return random.choice(remaining_questions)
    
    def create_attempt(self, question):
        attempted_question = AttemptedQuestion(question=question, quiz_profile=self)
        attempted_question.save()

class AttemptedQuestion(models.Model):
    quiz_profile = models.ForeignKey(Quizgame, on_delete=models.CASCADE, related_name='attempt')
    question = models.ForeignKey(Quiz, on_delete=models.CASCADE)
    choice = models.ForeignKey(Choice, on_delete=models.CASCADE, null=True)
    is_true = models.BooleanField(default=False)

In above where in class Quizgame I filter the questions in get_new_question method here I passed an course_id as an argument by I don't know how to filter out with the course_id for the particular course questions..

Answer 1

If you are trying to link a question to a course, I can't see a ForeignKey related to a Course object in your AttemptedQuestion class. You should add

class AttemptedQuestion(models.Model):
    # ...
    course = models.ForeignKey(Course, on_delete=models.CASCADE, null=True)

and then you can simply filter by

qs = AttemptedQuestion.objects.filter(course=course_id)

Answer 2

Before answering your question there is a simple tip that will help you raise the readability of your code.

If you're creating FK to a model named Course , name the field course . "course_name" is implying we will get a name in that field.

To access all the Quiz instances by course_id variable, you can use the __ operator in filter() method like this:

Quiz.objects.filter(course_name__id=course_id)

Note the double underscore __ after the "course_name". What this does is telling Django: "Filter Quiz where course_name's id is equal to 'course_id'".