Re: Using Aggregate and Count

Hi Daniel,

On Wed, Nov 20, 2013 at 5:47 PM, Daniel Roseman <daniel@roseman.org.uk> wrote:
> On Wednesday, 20 November 2013 19:11:26 UTC, Timothy W. Cook wrote:

>
> You're accessing a `review_count` attribute via each Paper instance, but you
> haven't set up anything that would do that - you only have a single
> top-level `review_count` dictionary.
>
> Instead of a separate `aggregate` call, you should be using `annotate` on
> the original Paper queryset:
>
> papers =
> Paper.objects.filter(project__id=self.kwargs['pk']).annotate(review_count=Count('review'))
>
> Now each element in `papers` has a `review_count` attribute.

I had actually tried this. However, this is a reverse relationship
The foreignkey is on Review to Paper. So if I use your suggestion or
even:
papers = Paper.objects.filter(project__id=self.kwargs['pk']).annotate(review_count=Count('review__paper'))

Which I first thought was correct. I get a FieldError:
FieldError at /papers/papers_list/1
Cannot resolve keyword 'review' into field. Choices are: abstract, authors, ...

I thought that the docs at:
https://docs.djangoproject.com/en/1.6/topics/db/aggregation/#following-relationships-backwards

say this would work but apparently Django can't find the Review->Paper
relationship.

I'm stumped.

--Tim

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