试图找出投票的总数，但无法理解它是如何在序列化器中完成的.我是Django的新手，它是如何完成的

这是我的模型:

class Answer(models.Model):
    question = models.ForeignKey(Question, on_delete=models.CASCADE, related_name='answers')
    answer = models.CharField(max_length=1000, default="", blank=False)
    author = models.ForeignKey(User, on_delete=models.SET_NULL, null=True)
    createdAt = models.DateTimeField(auto_now_add=True)
    upVotes = models.IntegerField(default=0)
    downVotes = models.IntegerField(default=0)

    def __str__(self):
        return str(self.answer)

以下是序列化程序:

class AnswerSerializer(serializers.ModelSerializer):

    votes = serializers.SerializerMethodField(method_name='get_votes', read_only=True)
    class Meta:
        model = Answer
        fields = ('id', 'question', 'answer', 'author', 'createdAt', 'votes')

    def get_votes(self, obj):
        if obj.upVotes and obj.downVotes:
            total_votes = (obj.upVotes + obj.downVotes)
            return total_votes

以下是我的赞成票:

@api_view(['POST'])
@permission_classes([IsAuthenticated])
def upvote(request, pk):
    answer = get_object_or_404(Answer, id=pk)
    author=request.user
    voter = upVote.objects.filter(author=author, answer=answer)        
    if voter.exists():
        return Response({
            'details':'You cannot vote twice'
        })
    else:
        upVote.objects.create(
            answer=answer,
            author=author
        )
        answer.upVotes += 1
        answer.save()
        return Response({
            'details':'Vote added'
        })

如何找到总票数，这应该定向到答案模型.如何在串行化程序中完成这类操作？