I\'m trying to use django annotation to create queryset field which is a list of values of some related model attribute.
queryset = ...
qs = queryset.annotat
I have done something like that:
qs = queryset \
.annotate(
field_a=ArrayAgg(Case(When(
related_model__field="A",
then="related_model__pk")
)),
field_b=ArrayAgg(Case(When(
related_model__field="B",
then="related_model__pk")
)),
field_c=ArrayAgg(Case(When(
related_model__field="C",
then="related_model__pk")
))
)
Now there are lists of None
or pk
under each field_a
, field_b
and field_c
for every object in queryset. You can also define other default value for Case
instead of None
.