如何在 django 模型中进行 2 层深度反向关系？

Question

我使用单个用户模型进行身份验证并使用用户模型创建多个“类型”帐户。每种类型都有不同的仪表板，因此要显示不同的内容。

Organization
-> Teacher
    -> Student

问 - 我想在组织帐户中列出教师及其对应的学生？它是一个 listView，所以我想知道如何使用 revere 关系列出组织帐户中特定教师下的所有学生？

class User(AbstractUser):
    ...


class Organization(models.Model):
    user_id = models.OneToOneField(
        settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name='superAdmin')
    ...

class Teacher(models.Model):
    user_id = models.OneToOneField(
        settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name='faculty')
    super_admin_id = models.ForeignKey(
        SuperAdmin, on_delete=models.CASCADE, related_name='faculty')
    ...


class Student(models.Model):
    user_id = models.OneToOneField(
        settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name='user')
    faculty_id = models.ForeignKey(
        Teacher, on_delete=models.CASCADE, related_name='student')
    ...

如果对如何改进现有模型架构有任何建议，我也想知道。

Answer 1

您可以像这样获取老师和他们的学生（在两个数据库中）：

teachers = Teacher.objects.filter(
    user_id__superAdmin=request.user.superAdmin
).prefetch_related('student')

for teacher in teachers:
    print(f'Teacher: {teacher.pk}')
    for student in teacher.student.all():
        print(f'Student: {student.pk}')

编辑：

您还可以annotate每位教师分配给他们的学生人数，这样：

teachers = Teacher.objects.filter(
    user_id__superAdmin=request.user.superAdmin
).annotate(num_students=Count('student'))

for teacher in teachers:
    print(f'Teacher {teacher.pk} has {teacher.num_students} students')