Django selecting newest values on a field by 'grouping' on the same table

convoluted_select.py

# We have a Django `Updates` model with `product`, `date`, `version` fields.
# We want to fetch the newest versions of products without executing many queries, in a Django way.
from django.db.models import CharField, Value as V
from django.db.models.functions import Concat

a = Updates.objects.values('product_id').annotate(cc=Concat('product_id', V('-'), Max('date'), output_field=CharField())).values('cc')
b = Updates.objects.annotate(cc=Concat('product_id', V('-'), 'date', output_field=CharField())).filter(cc__in=a)