在Django Rest Framework中串行化ManyToMany（2.3.5）抛出ValueError [英] Serializing ManyToMany in Django Rest Framework (2.3.5) throws ValueError

问题描述

我有我认为是一个非常简单的序列化程序设置，但是当我尝试将数据传输到我的API时，我收到以下错误：

ValueError：实例应该是一个queryset或其他可迭代的
many = True

这是视图：

  class QuizAPI（generics.RetrieveUpdateDestroyAPIView）：
 model = Quiz 
 serializer_class = QuizSerializer 
 lookup_field ='activity_id'
  

和序列化程序：

$ _ code> class MediaResourceSerializer（serializers.ModelSerializer）：
owner = serializers.PrimaryKeyRelatedField（many = False，read_only = True）

class Meta：
model = MediaResource
fields =（'owner'，'name'，'type'，'url'）

class AnswerSerializer（serializers.ModelSerializer）：
class元：
model =答案
fields =（'text' ，'is_correct'，'order'）

class QuestionSerializer（serializers.ModelSerializer）：
answers = AnswerSerializer（many = True，required = False）
resources = MediaResourceSerializer = true，required = False）

class Meta：
model = Question
fields =（
'question_id'，
'type'，
'order'，
'question_text'，
'explain'，
'resources'，
'grading_weight'，
'answers'
）

class QuizSerializer（serializers.ModelSerializer）：
questions = QuestionSerializer（many = True，required = False）
created_by = serializers.PrimaryKeyRelatedField（many = False，read_only = True）

class Meta：
model = Quiz
fields =（
'activity_id'，
'name'，
'is_hidden ，
'created_by'，
'created_date'，
'last_updated'，
'可共享'，
'问题'
）

如果我从QuizSerializer中注释出问题字段，它运行正常（当然没有问题数据）。

**编辑：
这是PUT呼叫有效负载：

  activity_id：4 
 created_by：1 
 created_date：2013-07-29T20：39：47.981Z
 is_hidden：false 
 last_updated：null 
 name：This只是一个测试
问题：[] 
可共享：true 
  

解决方案

问题在于，嵌套表示形式不支持读写，并将其序列化写入操作的平面结构是要走的路。

I have what I assumed to be a pretty simple serializer setup, but when I attempt to PUT data to my API, I get the following error:

ValueError: instance should be a queryset or other iterable with many=True

Here's the view:

class QuizAPI(generics.RetrieveUpdateDestroyAPIView):
    model = Quiz
    serializer_class = QuizSerializer
    lookup_field = 'activity_id'

and the serializers:

class MediaResourceSerializer(serializers.ModelSerializer):
    owner = serializers.PrimaryKeyRelatedField(many=False, read_only=True)

    class Meta:
        model = MediaResource
        fields = ('owner', 'name', 'type', 'url')

class AnswerSerializer(serializers.ModelSerializer):
    class Meta:
        model = Answer
        fields = ('text','is_correct','order')

class QuestionSerializer(serializers.ModelSerializer):
    answers = AnswerSerializer(many=True, required=False)
    resources = MediaResourceSerializer(many=True, required=False)

    class Meta:
        model = Question
        fields = ( 
            'question_id', 
            'type', 
            'order', 
            'question_text', 
            'explanation', 
            'resources', 
            'grading_weight', 
            'answers' 
        )

class QuizSerializer(serializers.ModelSerializer):
    questions = QuestionSerializer(many=True, required=False)
    created_by = serializers.PrimaryKeyRelatedField(many=False, read_only=True)

    class Meta:
        model = Quiz
        fields = (
            'activity_id', 
            'name',  
            'is_hidden', 
            'created_by', 
            'created_date', 
            'last_updated', 
            'sharable', 
            'questions'
        )

If I comment out the 'questions' field from QuizSerializer it runs just fine (of course without question data).

** Edit: Here's the PUT call payload:

activity_id: 4
created_by: 1
created_date: "2013-07-29T20:39:47.981Z"
is_hidden: false
last_updated: null
name: "This is only a test"
questions: []
sharable: true

解决方案

The problem looks to be that nested representations do not support read–write, and serializing flat structures for write operations is the way to go.

这篇关于在Django Rest Framework中串行化ManyToMany（2.3.5）抛出ValueError的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！