Jj's web stream

Django random object manager

Several times in the past I needed to fetch a list of random objects. And Today I decided to make a Mixin class to add a get_random() method to my managers:

# -*- coding: utf-8 -*-

from random import sample

class RandomObjectManager(object):


    Manager Mixin to implement get_random() in your models.

    You can override get_objects to tune the queriset

    To use, define your class:

    class MyManager(models.Manager, RandomObjectManager):

        DEFAULT_NUMBER = 5 # I can change that

        def get_objects(self):

            return self.filter(active=True) # Only active models plz

    class MyModel(models.Model):

        active = models.BooleanField()

        objects = MyManager()

    Now you can do:




    def get_objects(self):

        return self.all()

    def get_random(self, number=DEFAULT_NUMBER):


        Returns a set of random objects


        ids = self.get_objects().values_list('id', flat=True)

        amount = min(len(ids), number)

        picked_ids = sample(ids, amount)

        return self.filter(id__in=picked_ids)

I've added this as a Django snippet and as a Gist.


fish2000: Hey, nice implementation w/ the inner class sir. Just an FYI tho: in my own investigations with this sort of thing, I found that calling random.seed() in the manager's init() method was necessary, to ensure the most randomish results.

Thomas Woolford: Surely this is less of a performance killer than reading every ID from the entire table and then making another separate query to grab the objects that you actually need....

Thomas Woolford: ]

Jj: https://code.djangoproject.com/ticket/5267

Fernando Gutierrez: Aren't you supposed to use get_objects() instead?

Jj: Yes! I just fixed that, thanks