Django模型设计

Question

我工作在Django上的一个小测验应用程序，有以下模型-用户，测试，问题和答案。测试模型充当问题模型的包装器。我的模特们现在就是这样-

models.py

class Test(models.Model):
    def id_count():
        current_count = Test.objects.count()
        current_count += 1
        return current_count
    test_id = models.PositiveIntegerField(default=id_count,primary_key=True)
    test_description = models.CharField(max_length=255)


class Question(models.Model):
    def id_count():
        current_count = Question.objects.count()
        current_count += 1
        return current_count
    test = models.ForeignKey(Test,on_delete=models.CASCADE)
    question_id = 
    models.PositiveIntegerField(default=id_count,primary_key=True) 
    question_text = models.CharField(max_length=255)
    option_one = models.CharField(max_length=12,default="Always")
    option_two = models.CharField(max_length=12,default="Never")

class Answer(models.Model):
    question = models.ForeignKey(Question,on_delete=models.CASCADE)
    customuser = 
           models.ForeignKey(CustomUser,on_delete=models.CASCADE,blank=True, 
           null=True)
    original_answer_score = 
            models.IntegerField(default=-1)

目前的模型基本上允许每个用户多次回答相同的问题。如何设计我的模型，让每个用户只回答一个问题一次？谢谢。

编辑以添加相应的视图：

class AnswerFormView(SingleObjectMixin, generic.FormView):
template_name = 'tests/question_detail.html'
form_class = forms.AnswerForm
model = models.Answer

def get_success_url(self,*args,**kwargs):
    return reverse('tests:question_detail', args=(self.kwargs['pk'],))

def form_valid(self, form):
    answer = models.Answer.objects.create(
            question=models.Question.objects.get(question_id=self.kwargs['pk']),
            customuser=self.request.user,
            original_answer_score=form.cleaned_data['original_answer_score']
    )       
    return super(AnswerFormView, self).form_valid(form)

Answer 1

在回答表中使客户和问题成为一个复合索引。

类似于：

class Answer(...
    class Meta:
        unique_together = ( 'customuser', 'question' )
    ...

只要将正确的字段名放入元组中，数据库就会强制执行惟一性。

更多信息：https://docs.djangoproject.com/en/2.0/ref/models/options/#unique-together

Answer 2

请尝试为您的应答模型编写以下代码。

class Answer(models.Model):
    question = models.ForeignKey(Question,on_delete=models.CASCADE)
    customuser = models.ForeignKey(CustomUser,on_delete=models.CASCADE,blank=True, null=True)
    original_answer_score = models.IntegerField(default=-1, editable=False)


    class Meta:
        unique_together = **('question', 'customuser')**
        ordering = ('question')

要回答一个问题，只需在您的字段中添加editable=False，以便一旦输入就不能编辑它。

要将quetion和customuser结合起来，您需要在模型的Meta类中添加unique_together。