创建序列化器以显示正确的数据

问题描述

我有4个模型。 用户，问题，选择和投票。这基本上是我要创建的民意调查应用。一个问题可以有很多选择。 投票模型跟踪每个用户选择的答案。

I have 4 models. User, Question, Choice, and Voting. This is basically a polls app I'm trying to create. A question can have many choices. The Voting model tracks what each user chose as their answer.

我要做的是检索所有问题，并检查登录用户为每个问题选择的选择。这是模型：

What I'd like to do is retrieve all the questions and also check what choice the logged in user selected for each question. Here's the models:

class Question(models.Model):
    user            = models.ForeignKey(User, on_delete=models.CASCADE)
    status          = models.CharField(max_length=200)
    total_votes     = models.IntegerField(default=0)

class Choice(models.Model):
    question    = models.ForeignKey(Question, on_delete=models.CASCADE)
    choice      = models.CharField(max_length=120)
    vote_count  = models.IntegerField(default=0)

class Voting(models.Model):
    user    = models.ForeignKey(User, on_delete=models.CASCADE)
    choice  = models.ForeignKey(Choice, on_delete=models.CASCADE)

这是我想要显示数据的方式：

Here's how I want the data displayed:

{
    user: 2
    status: "Hello"
    total_votes: 101
    choices: [
                {
                    "id": 2,
                    "choice": "first choice",
                    "vote_count": 31,
                    "question": 3
                },
                {
                    "id": 4,
                    "choice": "second choice",
                    "vote_count": 70,
                    "question": 3
                }
            ],
    choice_selected: 2
}

在上面的数据中，登录用户在此特定问题中选择了选项2。

In the data above, the logged in user selected choice 2 in this specific question.

编辑：我尝试添加序列化程序，但显示的对象类型为'投票'不能JSON序列化

class ChoiceSerializer(serializers.ModelSerializer):
    class Meta:
        model = Choice
        fields = '__all__'

class QuestionSerializer(serializers.ModelSerializer):
    choices = ChoiceSerializer(source='choice_set', many=True)
    class Meta:
        model = Question
        fields = '__all__'


class GetProfileQuestions(ListAPIView):
    serializer_class = QuestionSerializer

    def get_queryset(self):
        return Question.objects.all()

此查询成功打印出每个问题及其选择。但是，如何使它也能打印出用户为每个问题选择的选项？

This query successfully prints out each question and its choices. However, how do I make it so that it also prints out which choice the user selected for each question?

class VotingSerializer(serializers.ModelSerializer):

    class Meta:
        model = Voting
        fields = '__all__'


class ChoiceSerializer(serializers.ModelSerializer):
    votes = VotingSerializer(source='voting_set', many=True)
    class Meta:
        model = Choice
        fields = '__all__'


class QuestionSerializer(serializers.ModelSerializer):
    choices = ChoiceSerializer(source='choice_set', many=True)
    choice_selected = serializers.SerializerMethodField()
    class Meta:
        model = Question
        fields = '__all__'

    def get_choice_selected(self, obj):
        choice_selected = Voting.objects.filter(choice__question=obj.id).filter(user=obj.user)
        return choice_selected

推荐答案

我认为您会在自己的QuestionSerializer类中使用它

I think you will want this in your QuestionSerializer class

 choice_selected = serializers.SerializerMethodField()

并在QuestionSerializer中定义类似于以下内容的方法……

and define a method that looks something like this in QuestionSerializer …

def get_choice_selected(self, obj):
        choice_selected = Voting.objects.filter(choice__question=obj.id).filter(user=obj.user)
        return choice_selected

以上未经测试。

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