Does Django queryset values_list return a list object?

Question

I have a Django app where users post photos, and other leave comments under the photos.

When a comment is left, I need to notify:

1. Everyone else who wrote in this thread
2. The owner of the photo, in case they're not included in (1)

For (1), I do:

#I slice by 25 because I arbitrarily deem anyone beyond that irrelevant. 
all_commenter_ids = PhotoComment.objects.filter(which_photo=which_photo).order_by('-id').values_list('submitted_by', flat=True)[:25]

Next, for (2), I try:

all_relevant_ids = all_commenter_ids.append(which_photo.owner_id)
all_relevant_ids = list(set(all_relevant_ids))

I end up with an error:

'ValuesListQuerySet' object has no attribute 'append'

I find this strange, because I'm extracting a values_list.

Isn't that a list object, and in that case, shouldn't the attribute append work in this scenario? Please explain what's wrong, and suggest alternatives.

Answer 1

The values_list method returns a ValuesListQuerySet. This means it has the advantages of a queryset. For example it is lazy, so you only fetch the first 25 elements from the database when you slice it.

To convert it to a list, use list().

all_commenter_ids = PhotoComment.objects.filter(which_photo=which_photo).order_by('-id').values_list('submitted_by', flat=True)[:25]
all_commenter_ids = list(all_commenter_ids)

You might be able to start the queryset from your User model instead of using values_list. You haven't shown your models, so the following code is a guess:

from django.db.models import Q

commenters = User.objects.filter(Q(id=which_photo.owner_id)|Q(photocomment=which_photo))