How to annotate on a single object and not a QuerySet in Django?

Question

When annotating something to a model in Django one would write something like this:

Post.objects.all().annotate(total_yes_votes=Count('vote', filter=Q(vote__vote_choice='yes')))

What if I want to annotate on a single object and not all() the objects:

Post.objects.get(id=id).annotate(total_yes_votes=Count('vote', filter=Q(vote__vote_choice='yes')))

By the way, it doesn't work.

Isn't it more efficient to annotate a single object rather than all()?

Iain Shelvington · Accepted Answer · 2019-12-29 20:48:19Z

2

Move the call to .get() to after the annotation

Post.objects.annotate(total_yes_votes=Count('vote', filter=Q(vote__vote_choice='yes'))).get(id=id)

answered Dec 29, 2019 at 20:48

Iain Shelvington

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2 Comments

ztefanie Over a year ago

I get AttributeError: 'Post' object has not attribute annotate

damd Over a year ago

@Steffi: That sounds like you're trying to do some_post.annotate, but you need to use .annotate on Post.objects, i.e. before the .get, not after.

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