2

我有一个模型名称学生：

class Student(models.Model):
    first_name = models.CharField(max_length=50)
    last_name = models.CharField(max_length=50)
    unique_id = models.CharField(max_length=15)
    email = models.EmailField(blank=True)
    grade = models.ForeignKey(Grade)
    hr_teacher = models.ForeignKey(User, related_name='hr_students')
    parent = models.ForeignKey(User, related_name='children')

    def __unicode__(self):
        return u'%s, %s (G-%s, %s)' % (self.last_name, self.first_name, self.grade.short_name, self.unique_id)

    def hr_teacher_absent(self):
        return self.hr_teacher.groups.filter(name='Absent Teachers').count() > 0

    def hr_booking(self):
        return self.booking_set.filter(teacher=self.hr_teacher,status__uses_space=True)

    def has_booking(self):
        return bool(self.hr_booking())

    def hr_booking_for_event(self, ptc_event):
        return self.hr_booking().filter(period__ptc_event=ptc_event)

    def has_booking_for_event(self, ptc_event):
        return bool(self.hr_booking_for_event(ptc_event))

    def delete_all_bad_bookings(self):
        bad_bookings = self.booking_set.exclude(teacher=self.hr_teacher).delete()

    class Meta:
        ordering = ['grade','last_name','first_name']

每个学生都有一个家庭教师，它是组名“教师”中的用户（这些是默认用户，在 django 的管理员中定义的组）。我正在尝试获取至少有 1 个学生的教师组中的用户列表。这是我的代码：

teacher_list_db = get_object_or_404(Group, name="Teachers").user_set.annotate(num_students=Count('hr_students')).filter(num_students__gt=0).order_by("last_name","first_name")

它返回一个空数组。

我阅读了 django 文档，发现了这个方法：

get_list_or_404(klass, *args, **kwargs)

我试过并被困在这里：

teacher_list_db = get_list_or_404(User.objects.order_by('last_name', 'first_name'), groups__name='Teachers')

我不知道如何处理计算学生人数的注释部分有同一位老师！

4

1 回答 1

2

好的，我刚刚想通了：

teachers_list_db = get_list_or_404(User.objects.order_by('last_name', 'first_name'), groups__name='Teachers')
if teachers_list_db:
    teachers_list = []
    for teacher in teacher_list_db:
        if teacher.hr_students.all().count() >= 0:
            teachers_list.append(teacher)

Teachers_list是我需要的列表。

耶！姜戈太棒了！！！\米/

于 2012-10-18T18:01:10.137 回答