Django，REST 框架 - 如何确保为图像返回绝对 url？答案

【问题标题】：Django, REST framework - How to ensure absolute url will be returned for image?Django，REST 框架 - 如何确保为图像返回绝对 url？
【发布时间】：2020-07-09 01:14:44
【问题描述】：

我需要 viewset 始终返回 avatar / avatar_thumbnail 图像字段的绝对 URL 作为响应，但我得到的是相对路径。我有两种这样的情况：1）在嵌套序列化程序的图像字段中，2）在视图集中，我想在检索方法中使用两个序列化程序。

models.py

class CustomUser(AbstractUser):
  avatar = ProcessedImageField(upload_to='users/',format='JPEG',options={'quality': 60})
  avatar_thumbnail = ImageSpecField(source='avatar',processors=[ResizeToFill(50, 50)],format='JPEG')

settings.py

MEDIA_URL = '/media/'
MEDIA_ROOT = os.path.join(BASE_DIR, 'media')

urls.py

if settings.DEBUG:
    from django.conf.urls.static import static
    urlpatterns += static(settings.MEDIA_URL, document_root=settings.MEDIA_ROOT)here

forum/api/serializers.py （嵌套序列化器）

class UserSerializer(serializers.ModelSerializer):
    avatar_thumbnail = serializers.ImageField(read_only=True)

    class Meta:
        model = CustomUser
        fields = ['id', 'username', 'avatar_thumbnail']

class ThreadSerializer(serializers.ModelSerializer):

    class Meta:
        model = Thread
        fields = ['id', 'title', 'subject', 'user']

    def to_representation(self, instance):
        representation = super().to_representation(instance)
        representation['user'] = UserSerializer(instance.user).data
        return representation

论坛/api/views.py

class ThreadViewSet(viewsets.ModelViewSet):
    serializer_class = ThreadSerializer
    queryset = Thread.objects.all()

对于 UserViewSet，“头像”的网址也有类似的问题。我需要绝对网址。我得到相对 url，但只有当我在视图集中覆盖检索方法时。（我覆盖它以对作为配置文件所有者的用户使用不同的序列化程序“UserPrivateSerializer”）。对于列表，我总是得到绝对 url。

users/api/serializers.py

class UserPublicSerializer(serializers.ModelSerializer):

class Meta:
    model = CustomUser
    fields = ['id', 'username', 'avatar']

class UserPrivateSerializer(serializers.ModelSerializer):    
    email = serializers.EmailField(required=True)

    class Meta:
        model = CustomUser
        fields = ['id', 'username', 'email', 'avatar']

用户/api/views.py （这里的问题在于我想在检索方法中使用的附加序列化程序）

class UserViewSet(viewsets.ModelViewSet):
    queryset = CustomUser.objects.exclude(username='user_deleted')
    serializer_class = UserPublicSerializer
permission_classes = [IsAuthenticated, IsOwnerOrReadOnly]

def retrieve(self, request, *args, **kwargs):
    """Custom retrieve method use UserPrivateSerializer if the user object is requested by it's owner.
    """
    super().retrieve(request, *args, **kwargs)
    instance = self.get_object()
    if request.user == instance:
        serializer = UserPrivateSerializer(instance)
    else:
        serializer = UserPublicSerializer(instance)
    return Response(serializer.data, status=status.HTTP_200_OK)

【问题讨论】：

标签： python django django-rest-framework django-imagekit

【解决方案1】：

我发现当我向序列化程序添加上下文时问题已经解决了。

论坛/api/serializers.py

class ThreadSerializer(serializers.ModelSerializer):

    class Meta:
        model = Thread
        fields = ['id', 'title', 'subject', 'user']

    def to_representation(self, instance):
        representation = super().to_representation(instance)
        representation['user'] = UserSerializer(instance.user, context=self.context).data
        return representation

users/api/views.py

class UserViewSet(viewsets.ModelViewSet):
    queryset = CustomUser.objects.exclude(username='user_deleted')
    serializer_class = UserPublicSerializer
    permission_classes = [IsAuthenticated, IsOwnerOrReadOnly]

    def retrieve(self, request, *args, **kwargs):
        super().retrieve(request, *args, **kwargs)
        instance = self.get_object()
        if request.user == instance:
            serializer = UserPrivateSerializer(instance, context={'request': request})
        else:
            serializer = UserPublicSerializer(instance, context={'request': request})
        return Response(serializer.data, status=status.HTTP_200_OK)

我在这里找到了答案：Django REST Framework and FileField absolute url “请求必须对序列化程序可用，因此它可以为您构建完整的绝对 URL。一种方法是在创建序列化程序时显式传递它”

【讨论】：