AttributeError: 'NoneType' object has no attribute 'build_absolute_uri' Django Rest Framework

Question

我有这个序列化程序将路径转换为 url，它可以自己工作，但是当我尝试将这个序列化程序嵌套在另一个序列化程序中时，我得到了这个错误。你知道为什么吗？我需要这个函数，否则它只会显示这个主要的 SpecialistSerializer 中图像的路径。

class EntityPhotosSerializer(serializers.ModelSerializer):
    image = serializers.SerializerMethodField('get_file_abs_url')


    class Meta:
        model = EntityPhoto
        fields = ('user', 'entity', 'image',)

    def get_file_abs_url(self, obj):
        request = self.context.get('request')
        return request.build_absolute_uri(obj.image.url)

class SpecialistSerializer(serializers.ModelSerializer):
    reviews_quantity = serializers.IntegerField(source="get_reviews_quantity")

    class Meta:
        model = Entity
        fields = '__all__'

    def to_representation(self, instance):
        data = super().to_representation(instance)
        data['photos'] = EntityPhotosSerializer(many=True, instance=instance.entityphoto_set.all()).data
        return data

回溯：

Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/core/handlers/exception.py", line 47, in inner
    response = get_response(request)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/core/handlers/base.py", line 179, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/views/decorators/csrf.py", line 54, in wrapped_view
    return view_func(*args, **kwargs)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/views/generic/base.py", line 70, in view
    return self.dispatch(request, *args, **kwargs)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/rest_framework/views.py", line 509, in dispatch
    response = self.handle_exception(exc)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/rest_framework/views.py", line 469, in handle_exception
    self.raise_uncaught_exception(exc)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/rest_framework/views.py", line 480, in raise_uncaught_exception
    raise exc
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/rest_framework/views.py", line 506, in dispatch
    response = handler(request, *args, **kwargs)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/rest_framework/generics.py", line 282, in get
    return self.retrieve(request, *args, **kwargs)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/rest_framework/mixins.py", line 56, in retrieve
    return Response(serializer.data)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/rest_framework/serializers.py", line 548, in data
    ret = super().data
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/rest_framework/serializers.py", line 246, in data
    self._data = self.to_representation(self.instance)
  File "/Users/jakubstrawa/programming/PythonKuba/api/specialists/serializers.py", line 35, in to_representation
    data['photos'] = EntityPhotosSerializer(many=True, instance=instance.entityphoto_set.all()).data
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/rest_framework/serializers.py", line 745, in data
    ret = super().data
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/rest_framework/serializers.py", line 246, in data
    self._data = self.to_representation(self.instance)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/rest_framework/serializers.py", line 664, in to_representation
    self.child.to_representation(item) for item in iterable
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/rest_framework/serializers.py", line 664, in <listcomp>
    self.child.to_representation(item) for item in iterable
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/rest_framework/serializers.py", line 515, in to_representation
    ret[field.field_name] = field.to_representation(attribute)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/rest_framework/fields.py", line 1870, in to_representation
    return method(value)
  File "/Users/jakubstrawa/programming/PythonKuba/api/specialists/serializers.py", line 23, in get_file_abs_url
    return request.build_absolute_uri(obj.image.url)
AttributeError: 'NoneType' object has no attribute 'build_absolute_uri'

Answer 1

在to_representation，您访问了EntityPhotosSerializer。在该序列化程序中，您正在尝试访问上下文。如果你想这样做，你需要将当前上下文传递给 SpecialistSerializer.

中的 EntityPhotosSerializer

    def to_representation(self, instance):
        data = super().to_representation(instance)
        data['photos'] = EntityPhotosSerializer(many=True, context=self.context, instance=instance.entityphoto_set.all()).data
        return data

AttributeError: 'NoneType' object has no attribute 'build_absolute_uri' Django Rest Framework

AttributeError: 'NoneType' object has no attribute 'build_absolute_uri' Django Rest Framework

python

django

django-rest-framework