如何修复Django的视图没有返回一个HttpResponse对象。它返回了None而不是？

Question

我收到以下错误：

视图KSUvity.authentication.views.registerAttendee未返回HttpResponse对象。它返回了None

我认为这是因为我的功能存在逻辑错误。我有几个if和else语句来检查几个条件。

这是views.py中的函数：

def registerAttendee(request,pk):
    act = Activity.objects.get(pk=pk)
    act.save()
    attendee, _ = Attendee.objects.get_or_create(student=request.user)

    volunteer = Volunteer.objects.filter(student=request.user)

    ActvsStudentAttending=Activity.objects.filter(attendee=attendee)
    ActvsStudentVolunteering=Activity.objects.filter(volunteer=volunteer)

    if act.volunteer.filter(student=request.user).exists():
        messages.error(request, 'You\'re already registered as a volunteer for this activity!', extra_tags='alert')
        return redirect('home/#work')

    elif act.attendee.filter(student=request.user).exists():
        messages.warning(request, 'You\'re already registered as an attendee for this activity!', extra_tags='alert')
        return redirect('home/#work')

    elif ActvsStudentAttending.exists():
        for x in ActvsStudentAttending:
            if x.startDate.date() == act.startDate.date():
                messages.error(request, 'You\'re already registered in the '+x.title+' activity that is held on the same day as '+act.title+'!', extra_tags='alert')
                return redirect('home/#work')

    elif ActvsStudentVolunteering.exists():
        for x in ActvsStudentVolunteering:
            if x.startDate.date() == act.startDate.date():
                messages.error(request, 'You\'re already registered in the '+x.title+' activity that is held on the same day as '+act.title+'!', extra_tags='alert')
                return redirect('home/#work')
    else:
        act.attendee.add(attendee)
        messages.success(request, 'You\'re successfully registered as an attendee!', extra_tags='alert')
        return redirect('home/#work')

是因为for循环中的内部if而引发错误？如果是，我该如何解决？我没有其他的这些案件，所以我不知道我在这里缺少什么。我必须检查所有条件，然后才能进入最终将其添加到模型中的其他条件。

我是Django和Python的新手，所以请原谅。

这就是我在models.py中所拥有的：

class Activity(models.Model):
    type = models.CharField(max_length=50, default="")
    title = models.CharField(max_length=200, default="")
    description = models.CharField(max_length=500)
    owner = models.ForeignKey(User, related_name="owner")
    college = models.CharField(max_length=200)
    location = models.CharField(max_length=200)
    room = models.CharField(max_length=200)
    startDate = models.DateTimeField(null=True, blank=True)
    endDate = models.DateTimeField(null=True, blank=True)
    attendee = models.ManyToManyField(Attendee, related_name="attendees",null=True, blank=True)
    volunteer = models.ManyToManyField(Volunteer, related_name="volunteers",null=True, blank=True)

class Attendee(models.Model):
    student = models.ForeignKey(User, related_name="attendee")

class Volunteer(models.Model):
    student = models.ForeignKey(User, related_name="volunteer")

Answer 1

删除else并取消其代码块。这将确保如果您的代码进入早期的elif块之一但从未在循环中传递内部if条件，则始终执行代码的这一部分：

if ...:
    # ...
elif ...:
    # ...
# remove the 'else', so that this will always run if your view function 
# did not return from any of the earlier '[el]if' blocks
act.attendee.add(attendee)
messages.success(request, 'You\'re successfully registered as an attendee!', extra_tags='alert')
return redirect('home/#work')