Django (DRF) - get_queryset - 尝试使用 model “产品”作为额外字段返回“图像”

Question

我正在尝试创建一个返回所有产品的查询集。 每个产品都有一个或多个 ProductImages，我想将它们添加为每个产品的额外字段“图像”。

所以我想要的回应就像[ { id: 1, name: "prod1", images: images } ]

我尝试了以下实现：

楷模

class Product(models.Model):
    name = models.CharField(max_length=255)
    description = models.TextField()
    price = models.FloatField()

class ProductImage(models.Model):
    name = models.CharField(max_length=255)
    product = models.ForeignKey(Product, on_delete=models.CASCADE)

我的想法以最简单的方式实现

class ProductViewSet(viewsets.ModelViewSet):
    serializer_class = ProductSerializer
    queryset = Product.objects.all()

    def get_queryset(self):
        queryset = Product.objects.all()
        product_list = []

        # iterate over all products
        for product in queryset:
            images = ProductImage.objects.filter(product=q.id)
            product['images'] = images
            product_list.append(product)

        return product_list

给出错误

"TypeError: 'Product' object does not support item assignment"

新想法，制作新的字典并添加产品元素并将“图像”添加为额外字段。

class ProductViewSet(viewsets.ModelViewSet):
    serializer_class = ProductSerializer
    queryset = Product.objects.all()

    def get_queryset(self):
        queryset = Product.objects.all()
        product_list = []

        # iterate over all products
        for q in queryset:
            images = ProductImage.objects.filter(product=q.id)
            product = {"id": q.id, "name": q.name, "description": q.description, "price": q.price, "images": images}
            product_list.append(product)

        return product_list

给出错误

Internal Server Error: /api/product/
Traceback (most recent call last):
  File "C:\Users\Simon\.virtualenvs\django_backend-ZmgaAA1F\lib\site-packages\django\core\handlers\exception.py", line 47, in inner
    response = get_response(request)
  File "C:\Users\Simon\.virtualenvs\django_backend-ZmgaAA1F\lib\site-packages\django\core\handlers\base.py", line 181, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "C:\Users\Simon\.virtualenvs\django_backend-ZmgaAA1F\lib\site-packages\django\views\decorators\csrf.py", line 54, in wrapped_view
    return view_func(*args, **kwargs)
  File "C:\Users\Simon\.virtualenvs\django_backend-ZmgaAA1F\lib\site-packages\rest_framework\viewsets.py", line 125, in view
    return self.dispatch(request, *args, **kwargs)
  File "C:\Users\Simon\.virtualenvs\django_backend-ZmgaAA1F\lib\site-packages\rest_framework\views.py", line 509, in dispatch
    response = self.handle_exception(exc)
  File "C:\Users\Simon\.virtualenvs\django_backend-ZmgaAA1F\lib\site-packages\rest_framework\views.py", line 469, in handle_exception
    self.raise_uncaught_exception(exc)
  File "C:\Users\Simon\.virtualenvs\django_backend-ZmgaAA1F\lib\site-packages\rest_framework\views.py", line 480, in raise_uncaught_exception
    raise exc
  File "C:\Users\Simon\.virtualenvs\django_backend-ZmgaAA1F\lib\site-packages\rest_framework\views.py", line 506, in dispatch
    response = handler(request, *args, **kwargs)
  File "C:\Users\Simon\.virtualenvs\django_backend-ZmgaAA1F\lib\site-packages\rest_framework\mixins.py", line 46, in list
    return Response(serializer.data)
  File "C:\Users\Simon\.virtualenvs\django_backend-ZmgaAA1F\lib\site-packages\rest_framework\serializers.py", line 768, in data
    ret = super().data
  File "C:\Users\Simon\.virtualenvs\django_backend-ZmgaAA1F\lib\site-packages\rest_framework\serializers.py", line 253, in data
    self._data = self.to_representation(self.instance)
  File "C:\Users\Simon\.virtualenvs\django_backend-ZmgaAA1F\lib\site-packages\rest_framework\serializers.py", line 686, in to_representation
    return [
  File "C:\Users\Simon\.virtualenvs\django_backend-ZmgaAA1F\lib\site-packages\rest_framework\serializers.py", line 687, in <listcomp>
    self.child.to_representation(item) for item in iterable
  File "C:\Users\Simon\.virtualenvs\django_backend-ZmgaAA1F\lib\site-packages\rest_framework\serializers.py", line 509, in to_representation
    attribute = field.get_attribute(instance)
  File "C:\Users\Simon\.virtualenvs\django_backend-ZmgaAA1F\lib\site-packages\rest_framework\relations.py", line 538, in get_attribute
    relationship = get_attribute(instance, self.source_attrs)
  File "C:\Users\Simon\.virtualenvs\django_backend-ZmgaAA1F\lib\site-packages\rest_framework\fields.py", line 95, in get_attribute
    instance = instance[attr]
KeyError: 'categories'

我已经搞砸了一段时间，有人能指出我如何做到这一点的正确方向吗？

Answer 1

向class Product添加另一个字段，这是一个名为extra的JSONField 。 然后，在 get_queryset() 方法中使用product.extra = {'images': [image.image.url for image in images]}方法。