I had a similar problem, and just used custom SQL. It's easy:
from django.db import connection
cursor = connection.cursor()
cursor.execute("""
SELECT cars_model.id, cars_model.opis,
cars_znamka.id, cars_znamka.opis,
COUNT(*)
FROM cars_model, cars_vozilo, cars_znamka
WHERE cars_model.id=cars_vozilo.model_id
AND cars_znamka.id = cars_model.znamka_id
GROUP BY cars_model.id, cars_model.opis, cars_znamka.id,
cars_znamka.opis
HAVING COUNT(*)>0
""")
result_list = []
for row in cursor.fetchall():
# create the dictionary object, that you'll pass to your
template.
dict_obj = {
"id" : row[0],
"opis" : "%s %s" % (row[3], row[1]),
"cars_count":row[4]
}
result_list.append(dict_obj)
# template expects "model_list"
model_list = result_list
Hope this helps,
Carlos
On 7/16/06, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
>
> Hi.
>
> This is probably trivial, but I've not managed to find the solution.
> How do I filter objects based on the count of a ManyToManyField?
>
> My example:
>
> I have two classes -- Blog and Submission:
>
> class Blog( models.Model ):
> entries = models.ManyToManyField( Submission )
>
> class Submission( models.Model ):
> [... whatever ]
>
> I want to fetch a list of all Blog instances which have at least one
> Submission , i.e. entries.count() > 0. Changing the model is not an
> option.
>
> I've been trying all kinds of permutations of filter, entries, count,
> gt, etc, such as:
> Blog.objects.filter(entries__count__gt = 0)
>
> No luck so far.
>
> Can somebody please help me?
>
> Thanks,
> Daniel
>
>
> >
>
--
Carlos Yoder
http://carlitosyoder.blogspot.com
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