How-to: Mulitple Objects Serialisation - bulk creation of a list of objects ?

[markdoerr]

I was lately trying to implement a multi / bulk create Service, similar as described at the DRF.
Simple ideas failed, like adding many=True to the class Meta.

https://www.django-rest-framework.org/api-guide/serializers/#dealing-with-multiple-objects

Does DSG support the (bulk) generation of multiple objects, like providing a list of objects to the Create Method ?
What is the best way to do that ? Using streams ?
I would include it into the DSG Example, once I have an idea.

Merci :)

[legau]

Hi,
there's no builtin way to do that with the generic services but it would be easy to implement.
(largely the same as the CreateMixin)

class BulkCreateMixin:
    
    @grpc_action(
         request=SelfSerializer,
         use_request_list=True, 
         response=SelfSerializer,
         use_response_list=True
     )
    async def BulkCreate(self, request, context):
        serializer = await self.aget_serializer(message=request, many=True)
        await sync_to_async(serializer.is_valid)(raise_exception=True)
        await self.aperform_create(serializer)
        return await serializer.amessage

    async def perform_bulk_create(self, serializer):
        await serializer.asave()

[markdoerr]

Merci, @legau,
I will try to apply this to the book example in the next days - that we have your "recipe" documented for the public.

[markdoerr]

btw. @legau,
I guess there is a (gRPC) size limit of the length list. So for larger lists, a stream would be necessary ?

[AMontagu]

Hello @markdoerr

You may want to look at this issue:
#241

and this documentation: https://django-socio-grpc.readthedocs.io/en/stable/features/grpc-action.html#use-request-and-response-list

Also the gRPC size limits is configurable in https://django-socio-grpc.readthedocs.io/en/stable/settings.html#server-options

[markdoerr]

Thanks, @AMontagu ,
I did not expect that you can set the size that big of 100MB - I had a size limit of 2-4 MB in my head:
(grpc/grpc-web#1182)
Increasing this limit would also solve my file-upload issue....
Are there any caveats in increasing the limit (like more overhead...) ?

[AMontagu]

If I remember correctly the main issue is that bigger message will have impact on your network flow and may increase delay on all your API. But not sure of me.