Question

我在StorySerializer中的GET /api/stories/169/上收到以下错误，评论如下：

AttributeError at /api/stories/169/
'ManyRelatedField' object has no attribute 'queryset'

在检查物体后，我发现如果我改变了......

fields['feature'].queryset = fields['feature'].queryset.filter(user=user)

到

fields['photos'].child_relation.queryset = fields['photos'].child_relation.queryset.filter(user=user)

......似乎有效。但是这种方法没有记录，我确信这不是正确的做法。

我有这些模型：

class Story(CommonInfo):
    user = models.ForeignKey(User)
    text = models.TextField(max_length=5000,blank=True)
    feature = models.ForeignKey("Feature", blank=True, null=True)
    tags = models.ManyToManyField("Tag")

class Feature(CommonInfo):
    user = models.ForeignKey(User)
    name = models.CharField(max_length=50)

class Photo(CommonInfo):
    user = models.ForeignKey(User)
    image = ImageField(upload_to='photos')
    story = models.ForeignKey("Story", blank=True, null=True, related_name='photos', on_delete=models.SET_NULL)

和StorySerializer：

class StorySerializer(serializers.HyperlinkedModelSerializer):
    user = serializers.CharField(read_only=True) 
    comments = serializers.HyperlinkedRelatedField(read_only=True, view_name='comment-detail', many=True)

    def get_fields(self, *args, **kwargs):
        user = self.context['request'].user
        fields = super(StorySerializer, self).get_fields(*args, **kwargs)

        ## Restrict the options that the user can pick to the Features
        ## and Photos that they own
        # This line works:
        fields['feature'].queryset = fields['feature'].queryset.filter(user=user)

        # This line throws the error:           
        fields['photos'].queryset = fields['photos'].queryset.filter(user=user)

        return fields

    class Meta:
        model = Story
        fields = ('url', 'user', 'text', 'comments', 'photos', 'feature', 'tags')

我做错了什么？我觉得这与ForeignKey关系的方向有关。

Answer 1

您可以尝试使用 drf-writable-nested package 代替覆盖 get_fields 方法，这将有助于更轻松地序列化嵌套关系并更好地处理 orm 字段方向。

Answer 2

你可以使用 django-filter

我认为在序列化器中编辑 get 不是实用的解决方案

Answer 3

重要的两点。

当从用户视图中过滤查询集时，所有外键对象检索将只生成特定用户的对象。因此无需过滤 get_fields 内的用户。

class StoryList(generics.ListAPIView):
    serializer_class = StorySerializer

     def get_queryset(self):
         # consider there is login check before code is reaching here
         # since this filtered by the user and any susbquent 
         # foreign key objects will belong only to this user
         return Story.objects.filter(user=self.request.user)

一旦对用户进行过滤，您就可以使用另一个序列化程序或 SerializerMethodField 来相应地构造数据。以下代码应该适用于您的情况。

 class UserSerializer(serializers.HyperlinkedModelSerializer):
     class Meta:
         # Allow only url and id
         fields = ['id', 'url']
         extra_kwargs = {'url': {'view_name': 'user-detail'}}

 class FeatureSerializer(serializers.HyperlinkedModelSerializer):
     class Meta:
         fields = ['id', 'url']
         extra_kwargs = {'url': {'view_name': 'feature-detail'}}

 class PhotoSerializer(serializers.HyperlinkedModelSerializer):
     class Meta:
         fields = ['id', 'url']
         extra_kwargs = {'url': {'view_name': 'photo-detail'}}

class StorySerializer(serializers.HyperlinkedModelSerializer):
    user = UserSerializer(read_only=True) 
    comments = serializers.HyperlinkedRelatedField(read_only=True, 
                           view_name='comment-detail', many=True)
    # this work because of related names
    features = FeatureSerializers(many=True)
    photos = PhotoSerializers(many=True)
    # add tags serializer as well
    text = serializers.CharField()

    class Meta:
         fields = ['id', 'users', 'photos', 'features', ...]

Answer 4

我遇到了类似的问题，找到了一个与嵌套序列化程序的默认查询集有关的解决方案（链接）：How do you filter a nested serializer in Django Rest Framework?

而不是编辑get_fields 在故事序列化程序上，添加功能和照片字段，以引用故事序列化程序上的功能和照片序列化程序。例如 StorySerializer： features = FeatureSerializer(many=true, read_only=true) 然后为功能和照片覆盖list_serializer_class：

class FeatureFilteredListSerializer(serializers.ListSerializer):
    def to_representation(self, data):
        data = data.filter(user=self.context['request'].user)
        return super(FeatureFilteredListSerializer, self).to_representation(data)

// And then reference this from the actual FeatureSerializer meta:
class FeatureSerializer(serializers.ModelSerializer):

     ...

     class Meta:
         model = Work
         list_serializer_class = FeatureFilteredListSerializer
         fields = (...)

然后，当您到达故事终点时，它将获得此过滤后的嵌套序列化器列表

Django Request Framework＆＃39; ManyRelatedField＆＃39;对象没有属性＆＃39; queryset＆＃39;在get_fields中修改queryset时

4 个答案: