howto: group by in django - Evan Reiser

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howto: group by in django
Jan 05, 2009 05:23 AM UTC

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Evan Reiser

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Via Evan Reiser's Blog:

Django doesnt officially yet support group by, however the code to acomplish this is actually hidden inside. Â If you had a model that tracked registrations, which contained a FK to the user that refered the new user such as:

class Registration(models.Model):

Â Â Â Â Â ...

Â Â Â Â Â referer = models.ForeignKey(User,null=True,blank=True)

>>>Â from registration.models import Registration

>>> query_set = Registration.objects.extra(select={'count': 'count(1)'}, order_by=['-count'],where=['referer_id is not null']).values('count', 'referer') Â

>>> query_set.query.group_by = ['referer_id']

>>> for row in query_set:

... Â print row Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â

...Â

{'count': 26L, 'referer': 6384}

{'count': 4L, 'referer': 6871}

{'count': 3L, 'referer': 9993}

{'count': 2L, 'referer': 7804}

{'count': 2L, 'referer': 7892}

{'count': 2L, 'referer': 9699}

{'count': 1L, 'referer': 6111}

{'count': 1L, 'referer': 7821}

{'count': 1L, 'referer': 5025}

this is as ofÂ

Last Changed Rev: 9037

Last Changed Date: 2008-09-15 14:06:02 -0400 (Mon, 15 Sep 2008)

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