Re: Get count using annotate

On Thu, Jul 19, 2012 at 5:00 PM, karan <htc.karanagarwal@gmail.com> wrote:
> Hi,
>
> my models is-
>
> class Students(models.Model):
> country = models.ManyToManyField( Country )
>
> I want to calculate the total number of student objects for each of the
> country objects.
>
> I need the count of students interested in each country so far in my
> database.
>
> I was trying something with annotate but couldnt get far.
>
> I need suggestions :)
>
> Thanks . cheers !
>

Country.objects.annotate(num_students=Count('students'))

https://docs.djangoproject.com/en/1.4/topics/db/aggregation/#cheat-sheet

FYI: Your class name should be singular, as anything that 'Students'
has a foreign key to would access the related student instances by
'foo_object.studentss_set' (note the double s).

Cheers

Tom

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