M2M Joins

from django.db import models
from django.db.models.import Count


class Tag(models.Model):
    name = models.CharField(max_length=255, default='')

    def __unicode__(self):
        return self.name


class Article(models.Model):
    title = models.CharField(max_length=255, default='')
    body = models.TextField(default='')
    tag = models.ManyToManyField(Tag)

    def __unicode__(self):
        return self.title


a = Article.objects.get(pk=3)
a.tag.through.objects.all().values('tag_id').annotate(article_count=Count('article')).order_by('-article_count')[0]