如何使用模型序列化器在 django-rest 中序列化一对多关系？答案

【问题标题】：How to serialize a one to many relation in django-rest using Model serializer?如何使用模型序列化器在 django-rest 中序列化一对多关系？
【发布时间】：2017-02-13 01:56:29
【问题描述】：

这些是我的模型和序列化程序。我想要问题模型的表示以及被问到问题的人员列表。

我正在尝试这个：

@api_view(['GET', 'PATCH'])
def questions_by_id(request,user,pk):
    question = Question.objects.get(pk=pk)
    if request.method == 'GET':
        serializer = QuestionSerializer(question)
        return Response(serializer.data)

但我得到一个空字典 ({})。但是，当我从QuestionSerializer 中删除asked 字段时，我得到了Question 的完整表示以及Places 很好地序列化。我错过了什么？

class AskedToSerializer(serializers.ModelSerializer):
    class Meta:
        model = AskedTo
        fields = ('to_user', 'answered')

class QuestionSerializer(serializers.ModelSerializer):
    class Meta:
        model = Question
        places = PlaceSerializer(many=True, required=False)
        asked = AskedToSerializer(source='askedto_set', many=True)
        fields = ('id', 'created_on', 'title', 'places', 'answered','asked')
        extra_kwargs = {'created_by': {'read_only': True}}

class Question(BaseModel):
    title = models.CharField(max_length=200, null=False)
    places = models.ManyToManyField(Place, blank=True)
    answered = models.BooleanField(default=False)

class AskedTo(BaseModel):
    ques = models.ForeignKey(Question, on_delete=models.CASCADE)
    to_user = models.ForeignKey(settings.AUTH_USER_MODEL)
    replied = models.BooleanField(default=False)


class Place(models.Model):
    g_place_id = models.CharField(max_length=20,primary_key=True)
    json = models.TextField(null=True)
    name = models.CharField(max_length=40)

【问题讨论】：

标签： python serialization django-rest-framework one-to-many django-serializer

【解决方案1】：

我想通了。有两个错误。

改变了这个：

class AskedToSerializer(serializers.ModelSerializer):
    class Meta:
        model = AskedTo
        fields = ('to_user', 'answered')

对此（注意字段的变化，模型和序列化器上的字段不匹配）

class AskedToSerializer(serializers.ModelSerializer):
    class Meta:
        model = AskedTo
        fields = ('to_user', 'replied')

其次，我需要在class Meta之外定义任何额外的字段

class QuestionSerializer(serializers.ModelSerializer):
    places = PlaceSerializer(many=True, required=False)
    asked = AskedToSerializer(source='askedto_set', many=True)    

    class Meta:
        model = Question
        fields = ('id', 'created_on', 'title', 'places', 'answered','asked')
        extra_kwargs = {'created_by': {'read_only': True}}

注意places 和asked 定义的变化。

【讨论】：

【解决方案2】：

就我而言，我有这个 models.py：

class Section(models.Model):
     title = models.CharField(max_length=500)
     description = models.TextField(blank=True)
     user = models.ForeignKey(Profile, related_name="sections", on_delete=models.CASCADE)

class Feed(models.Model):
     title = models.CharField(max_length=500)
     link_rss = models.URLField(max_length=500)
     link_web = models.URLField(max_length=500)
     description = models.TextField(blank=True)
     language = models.CharField(max_length=50, blank=True)
     logo = models.URLField(blank=True)

     sections = models.ManyToManyField(Section, related_name="feeds")

我完成了 serializers.py 这个：

class FeedSerializer(serializers.ModelSerializer):
     sections = serializers.PrimaryKeyRelatedField(many=True, read_only=True)

     class Meta:
         model = Feed
         fields = '__all__'


class SectionSerializer(serializers.ModelSerializer):
     feeds = FeedSerializer(many=True, read_only=True)

     class Meta:
         model = Section
         exclude = ('user',)

【讨论】：