Order queryset by list of IDs

.py

# https://stackoverflow.com/questions/4916851/django-get-a-queryset-from-array-of-ids-in-specific-order/37648265#37648265

from django.db.models import Case, When

pk_list = [10, 2, 1]
preserved = Case(*[When(pk=pk, then=pos) for pos, pk in enumerate(pk_list)])
queryset = MyModel.objects.filter(pk__in=pk_list).order_by(preserved)


# pre django 1.8:
# def order_by_ids(queryset, ids):
#     db_column = queryset.model._meta.pk.db_column
#     ordering = 'CASE %s END' % ' '.join(['WHEN "%s"=%s THEN %s' % (db_column, pk, i) for i, pk in enumerate(ids)])
#     return queryset.filter(pk__in=ids).extra(select={'ordering': ordering}, order_by=('ordering',))