Django问卷投票异常：正确投票无法计入correct_votes问题排查

开发Django问卷系统时，Question表通过answer字段存储管理员配置的正确答案。投票逻辑要求：

• 若用户选择的选项与answer匹配，将该选项的correct_votes加1，并打印"correct"
• 若不匹配，将该选项的votes加1，并打印"not correct"

但实际运行时，无论投票是否正确，始终打印"not correct"，正确投票无法计入correct_votes，仅触发votes累加。

相关代码 #

view.py #

def vote(request, question_id):
    question = Question.objects.get(pk=question_id)
    try:
        selected_choice = question.choice_set.get(pk=request.POST['choice'])
    except (KeyError, Choice.DoesNotExist):
        return render(request, 'home_tests/question.html', {
            'question': question,
            'error_message': "You didn't select a choice.",
        })
    else:
        if selected_choice.votes == question.answer:
            print('correct')
            selected_choice.correct_votes += 1
            # selected_choice.save()
        elif selected_choice.votes != question.answer:
            print('not correct')
            selected_choice.votes += 1
    selected_choice.save()
    return HttpResponseRedirect(reverse('home_tests:results', args=(question.id,)))

models.py #

class Question(models.Model):
    objects = None
    language = models.ForeignKey(Language, null=True, blank=True, on_delete=models.CASCADE)
    question_text = models.CharField(max_length=200, null=True, blank=True)
    answer = models.CharField(max_length=250, null=True, blank=True)
    pub_date = models.DateTimeField('date published', null=True, blank=True)


class Choice(models.Model):
    DoesNotExist = None
    language = models.ForeignKey(Language, null=True, blank=True, on_delete=models.CASCADE)
    question = models.ForeignKey(Question, on_delete=models.CASCADE, null=True, blank=True)
    choice_text = models.CharField(max_length=250, null=True, blank=True)
    votes = models.IntegerField(default=0, null=True, blank=True)
    correct_votes = models.IntegerField(default=0, null=True, blank=True)
    user = models.ForeignKey(User, on_delete=models.CASCADE, null=True, blank=True)

请求日志 #

Quit the server with CONTROL-C.
[09/Jan/2023 18:49:27] "GET /home_tests/home/ HTTP/1.1" 200 2591
[09/Jan/2023 18:49:28] "GET /home_tests/10/ HTTP/1.1" 200 785
not correct
[09/Jan/2023 18:49:40] "POST /home_tests/10/vote/ HTTP/1.1" 302 0
[09/Jan/2023 18:49:40] "GET /home_tests/10/results/ HTTP/1.1" 200 521

解决方案 #

问题出在判断条件的错误使用：

• selected_choice.votes是Integer类型的投票计数，而question.answer是CharField类型的正确答案文本
• 两者类型不匹配、内容无关联，导致判断永远不成立，只会走else分支

修改vote函数中的判断逻辑，将selected_choice.votes替换为selected_choice.choice_text（选项的文本内容）与question.answer对比：

def vote(request, question_id):
    question = Question.objects.get(pk=question_id)
    try:
        selected_choice = question.choice_set.get(pk=request.POST['choice'])
    except (KeyError, Choice.DoesNotExist):
        return render(request, 'home_tests/question.html', {
            'question': question,
            'error_message': "You didn't select a choice.",
        })
    else:
        # 对比选项文本和正确答案
        if selected_choice.choice_text == question.answer:
            print('correct')
            selected_choice.correct_votes += 1
        else:
            print('not correct')
            selected_choice.votes += 1
    selected_choice.save()
    return HttpResponseRedirect(reverse('home_tests:results', args=(question.id,)))

额外优化点：

1. 去掉多余的elif判断，直接用else覆盖不匹配场景
2. 原代码中注释的selected_choice.save()无需单独调用，最后统一保存即可

内容的提问来源于stack exchange，提问作者Darina Martymianova