Question

Given this somewhat simplified representation of my application’s models, my question is how do I globally find the most popular MyModel? I.e., those MyModels are favorited the most by MyUsers.

I’ve come across similar blog posts about how to find favorite tags, but I don’t think those apply to this particular situation.

class MyUser(models.Model):
  favorite_models = models.ManyToManyField(MyModel)
  ...


class MyModel(models.Model):
  name = models.CharField(...)
  ...

Can this be done in a single query? Or do I need to loop over every MyUser and MyModel to determine the most popular? Thanks in advance!

Answer 1

I’m too lazy to create a django project from scratch, but this one should do the job:

from django.db.models import Count
MyModel.objects.annotate(Count('myuser'))

(or this)

MyModel.objects.annotate(Count('myuser_set'))

if not, try this:

class MyUser(models.Model):
    favorite_models = models.ManyToManyField(MyModel, related_name='myuser')

and then

MyModel.objects.annotate(Count('myuser_set'))

(let me know if it works, in any case this page should contain what you need to do that: https://docs.djangoproject.com/en/dev/topics/db/aggregation/)