Using distinct on annotations

Question

I am trying to get a distinct list of items. The db has a created field which is datetime and I need it as a date for my query. So I added an annotation. The problem is that distinct won't work on the annotation...

distinct_failed_recharges = recharges.filter(
    status=FAILED
).annotate(
    created_date=TruncDate('created')
).distinct(
    'created_date', 'sim', 'product_type', 'failure_reason'
).values_list('id', flat=True)

This is the error that I get:

django.core.exceptions.FieldError: Cannot resolve keyword 'created_date' into field

score 1 · Answer 1 · answered Feb 01 '18 at 10:23

I get the same error in django 1.11 doing:

qs = queryset.annotate(day=TruncDay('date')).distinct('day')
ids = list(qs.values_list('id', flat=True))

results with this error:

FieldError: Cannot resolve keyword 'day' into field.

This is very weird since I try to evaluate 'id'...

The only workaround that I've found is:

qs = queryset.annotate(day=TruncDay('date')).distinct('day')
objects_list = list(qs)
ids = [object.id for object in objects_list]

This is very inefficient, but hopefully my list is not too long...

Using distinct on annotations

1 Answers1