Django (REST Framework) - How to add fields to queryset iteration-CodePudding

I need some advice for making a query in Django (DRF).

I'm trying to make a queryset for Products, where every Product gets a field "images" with all the Images (Files) for that product (coupled using ProductImage model), but I can't figure out how to add the field.

Below is my ProductViewSet

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:

            # find Image ids for product
            image_ids = list(ProductImage.objects.filter(product=product.id).values_list('image', flat=True))
            images = []

            # iterate over images and add to images list
            for image_id in image_ids:
                image = list(File.objects.filter(id=image_id).all())
                images.append(image)

            # add images field to product
            # product['images'] = images # "TypeError: 'Product' object does not support item assignment"
            product.images = images # Doesn't do anything.

            # add product to product list
            product_list.append(product)

        return product_list

I've tried to do the following to add the field "images":

        product['images'] = images

which gives the error "TypeError: 'Product' object does not support item assignment"

        product.images = images

which doesn't do anything...

Could anyone point me in the right direction? Any tips on how to make this query in a better way are also welcome!

CodePudding user response：

Does your 'Product' model have an existing 'images' field with the correct data type?

If not, you won't be able to update it with a list of FileObjects.

A better solution might be a many-to-one model relationship between 'ProductImage' and 'Product'.

Then, Django will be better able to automagically return your images through the ORM rather than complicated bespoke queries. https://docs.djangoproject.com/en/4.0/topics/db/examples/many_to_one/

CodePudding user response：

It's hard to give an exact answer without seeing the other models, but if you write a more robust query, and use annotate, the annotated fields will be accessible on both the filtersets and serializers.

CodePudding user response：

try to use a dict, product_list = {} product_list[product] = images

remove

        product.images = images # Doesn't do anything.

        # add product to product list
        product_list.append(product)