get_list_or_404以多個濾波器在Django

Question

我有一個型號名稱學生：

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'] 

每個學生都有一個家房老師這是在組名「教師」用戶（這些都是默認用戶，在Django的定義的組管理員）。我試圖獲得至少有1名學生的小組教師中的用戶名單。這是我的代碼：

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") 

它返回一個空數組。

我讀了Django文檔並發現了這種方法：

get_list_or_404(klass, *args, **kwargs) 

我試過，結果被困在這裏：

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

我不知道如何使用，其對註釋的部分做學生的數量有相同的老師！

Answer 1

OK，我只是想通了：

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是我需要的清單。

耶！ Django真是太棒了！ \ m/