我尝试用prefetch_related做一个嵌套的序列化器，但它不起作用，下面是我的代码：
models.py

from django.db import models

class Student(models.Model):
    phone = models.IntegerField(null=True)
    birth_date = models.DateField(null=True)
    user = models.OneToOneField(get_user_model(), on_delete=models.CASCADE, related_name="student")

class Course(models.Model):
    title = models.CharField(max_length=100, blank=True, default='')

class CourseEnroll(models.Model):
    course = models.ForeignKey(Course, on_delete=models.PROTECT, related_name='course_enroll')
    student = models.ForeignKey(Student, on_delete=models.PROTECT, related_name='student_enroll')

views.py

from rest_framework import mixins
from rest_framework.viewsets import GenericViewSet

from quiz.models import Course
from quiz.serializers import CourseSerializer

class CourseViewSet(mixins.CreateModelMixin,
                    mixins.ListModelMixin,
                    mixins.RetrieveModelMixin,
                    GenericViewSet):

    def get_queryset(self):
        queryset = Course.objects.prefetch_related("course_enroll").all()
        return queryset
    serializer_class = CourseSerializer

serializers.py

from rest_framework import serializers

from quiz.models import Course, CourseEnroll

class CourseEnrollSerializer(serializers.ModelSerializer):
    class Meta:
        model = CourseEnroll
        fields = ['id']

class CourseSerializer(serializers.ModelSerializer):
    student_enrolled = CourseEnrollSerializer(many=True, read_only=True)

    class Meta:
        model = Course
        fields = ['id', 'title', 'student_enrolled']

以下是我的repo：https://github.com/congson95dev/regov-pop-quiz-backend-s-v1
我做错什么了吗？请帮忙，谢谢。