Django queryset filter : group by max limit 1

views.py

"""
class SampleCategoryModel
  id = primary
  
class SamplePostModel
  category = foreignkey(SampleCategoryModel)
  created_at = datetimefield
"""
from django.db.models import Max

query_set = SamplePostModel.objects.all()

condition = query_set.values('category').annotate(last_row_at=Max('created_at'))

query_set = query_set.filter(created_at__in=condition.values('last_row_at'))