Django annotate Count query output

Question

I have confusion in result of these queries:

>>> [f.count for f in Favourite.objects.annotate(count = Count('object_id'))]
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]

and second one is

>>> [f['count'] for f in Favourite.objects.values('object_id').annotate(count=Count('object_id'))]
[1, 5, 2, 1, 4, 2, 2, 3]

but according to django docs first query should work fine, and Favourite object have count of object_id.

Can anyone explain why the second query is working, but not the first?

Thanks!

Daniel Roseman · Accepted Answer · 2011-10-26 16:04:37Z

4

The second one is doing a group by on object_id. This is the expected behaviour. The first one is simply counting object_id for each row in the database.

answered Oct 26, 2011 at 16:04

Daniel Roseman

602k68 gold badges911 silver badges924 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Botond Béres Over a year ago

@Ahsan: The example you refer to in the docs uses annotation on a ManyToManyField so you can get counts > 1 for a single record, without grouping. For "normal" fields which are actual columns in the db table, you can obviously have just a count of 1 value per row without grouping by something.

Ahsan Over a year ago

@Béres Botond: I have also tried same as docs >>> [ge.c for ge in Album.objects.annotate(c=Count('genre'))] output: [1, 1, 1, 1, 1, 1, 1, 1] here genre have ManyToManyField relationshis with Album. And it works when i did >>> [ge['c'] for ge in Album.objects.values('genre').annotate(c=Count('genre'))] output: [1, 6, 1]

Collectives™ on Stack Overflow

Django annotate Count query output

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related