Question

我是django的初学者，是DRF的新手。因此，问题出在嵌套序列化器的create（）方法中。关键是它会创建新的标签实例，但不会将它们附加到我想在POST请求中发送到服务器的问题实例上。

这是我的模特：

class Question(models.Model):
    title = models.CharField(max_length=100)
    content = models.CharField(max_length=500, default="Write your question")  # HTMLField() look  TinyMCE
    tags = models.ManyToManyField("Tag")
    pub_date = models.DateField(auto_now=False, auto_now_add=True)
    author = models.ForeignKey(User, on_delete=models.CASCADE)
    answers = models.ManyToManyField("Answer")
    comment_cnt = models.IntegerField(default=0)
    like_cnt = models.IntegerField(default=0)
    def __str__(self):
        return self.title

    def get_absolute_url(self):
        return reverse('questions', args=[self.title])

    class Meta:    
        ordering = ['pub_date']

class Answer(models.Model):
    content = models.CharField(max_length=500, default="Write the answer")  # HTMLField() look  TinyMCE
    pub_date = models.DateField(auto_now=False, auto_now_add=True)
    author = models.ForeignKey(User, on_delete=models.CASCADE)
    like_cnt = models.IntegerField(default=0)
    def __str__(self):
        return self.author.username

class Tag(models.Model):
    name = models.CharField(max_length=50)
    discription = models.CharField(max_length=500, default="This is description")
    use_cnt = models.IntegerField(default=0)
    def __str__(self):
        return self.name

这里是序列化器：

class TagSerializer(serializers.ModelSerializer):
    class Meta:
        model = Tag
        fields = '__all__' 
        read_only_fields = ['use_cnt']

class AnswerSerializer(serializers.ModelSerializer):
    class Meta:
        model = Answer
        fields = '__all__' 

class QuestionSerializer(serializers.ModelSerializer):
    tags = TagSerializer(many=True )
    answers = AnswerSerializer(many=True, read_only=True)

    class Meta:
        model = Question
        fields = '__all__' 

    def create(self, validated_data):
        tags_data = validated_data.pop('tags')
        question = Question.objects.create(**validated_data)
        for tag_data in tags_data:
            Tag.objects.create(question=question, **tag_data)
        return question

这是我的观点：

class QuestionList(mixins.ListModelMixin,
                   mixins.CreateModelMixin,
                   generics.GenericAPIView):

    queryset = Question.objects.all()
    serializer_class = QuestionSerializer
    # permission_classes = [AllowAny]

    def get(self, request, *args, **kwargs):
        return self.list(request, *args, **kwargs)

    def post(self, request, *args, **kwargs):
        return self.create(request, *args, **kwargs)

class QuestionDetail(mixins.RetrieveModelMixin,
                     mixins.UpdateModelMixin,
                     mixins.DestroyModelMixin,
                     generics.GenericAPIView):

    queryset = Question.objects.all()
    serializer_class = QuestionSerializer
    # permission_classes = [IsOwnerOrReadOnly]
    lookup_field = 'title'

    def get(self, request, *args, **kwargs):
        return self.retrieve(request, *args, **kwargs)

    def put(self, request, *args, **kwargs):
        return self.update(request, *args, **kwargs)

    def delete(self, request, *args, **kwargs):
        return self.destroy(request, *args, **kwargs)

class TagList(mixins.ListModelMixin,
              mixins.CreateModelMixin,
              generics.GenericAPIView):

    queryset = Tag.objects.all()
    serializer_class = TagSerializer
    # permission_classes = [AllowAny]

    def get(self, request, *args, **kwargs):
        return self.list(request, *args, **kwargs)

    def post(self, request, *args, **kwargs):
        return self.create(request, *args, **kwargs)

我在POST请求中发送此邮件：

{
"tags": [{
    "name": "new tag",
    "discription": "description"
},
{
    "name": "another tag",
    "discription": "description"
}],
"title": "new one",
"content": "new content",
"comment_cnt": 2,
"like_cnt": 2,
"author": 2
}

并收到此消息：

"id": 14,
"tags": [],
"answers": [],
"title": "new one",
"content": "new content",
"pub_date": "2019-07-26",
"comment_cnt": 2,
"like_cnt": 2,
"author": 2

和标签分别：

{
    "id": 9,
    "name": "new tag",
    "discription": "description",
    "use_cnt": 0
},
{
    "id": 10,
    "name": "another tag",
    "discription": "description",
    "use_cnt": 0
}

谢谢！

Answer 1

您的代码模型没有question，因此无法正常工作。

尝试改为执行此操作：

   def create(self, validated_data):
        tags_data = validated_data.pop('tags')
        question = Question.objects.create(**validated_data)
        for tag_data in tags_data:
            tag = Tag.objects.create(**tag_data)
            question.tags.add(tag)

        question.save()

        return question

Answer 2

使用

tags = models.ManyToManyField(Tag)

也

for tag_data in tags_data:
        tag = Tag.objects.create(**tag_data)
        question.tags.add(tag)
question.save()

为什么我没有获得附加到问题实例的标签实例？

2 个答案: