What's the proper way to generate a response with a csv from an in-memory file-like object?

[hoIIer]

I have a button on my site that a user clicks to "export to csv"

I grab a record from dynamodb and use python's csv and io.StringIO() to generate an in-memory csv file of the data.

When I test locally using uvicorn I get the response with giant csv file. However when I test on aws (uses lambda), I get an error with OSError: [Errno 36] File name too long: b'id,batch_id,qrcode_svg\...

Does this look right or am I doing it wrong?

py 3.9

class CSVRoute(HTTPEndpoint):
    async def get(self, request):
        batch_id = request.path_params['id']

        csv = shop_schemas.ExportClaimBatchCSV().load({
            'batch_id': batch_id,
        })

        return FileResponse(
            csv,  # instance of io.StringIO().read().encode('ascii')
            filename=f'batch_{batch_id}.csv',
            media_type='text/csv',
            status_code=status.HTTP_200_OK,
        )