Patch for Django-1.4.2 that allows you to use Postgres's array_accum function. It adds function ArrayAccum in django.db.models. Using ArrayAccum will only work on Postgresql.
Django is a high-level Python Web framework that encourages rapid development and clean, pragmatic design. This patch (pkg name Django-ArrayAccum on pypi) allows you to use the array_accum function available in Postgresql. This function will NOT work in other databases. If you are happy with Postgresql and want to be able to use the array_accum within Django (and not write custom sql) this fork is for you to try.
This patch was created for Django-1.4.2. Install Django-1.4.2 before you install this patch.
This patch modifies three files.
This adds a function called ArrayAccum which you can then use in any query involving aggregations (similar to Sum, Avg etc which are built-in).
Example Usage: Suppose you have a model defined as such:
class People(models.Model): first_name = models.CharField(max_length=100) last_name = models.CharField(max_length=100)
And lets say you want to show the most common last names, count, associated first names — then here is how you can do it:
from django.db.models import Count, ArrayAccum results = People.objects.values("last_name").annotate(count=Count('id'), unique_first_names=ArrayAccum("first_name", distinct=True)).order_by('-count')