Python-сообщество

class Task(models.Model):
    users = models.ManyToManyField('auth.User', related_name='tasks',
        through='TaskUser')
    int_field = models.IntegerField()
class TasktUser(models.Model):
    task = models.ForeignKey('Task', related_name='middle_users')
    user = models.ForeignKey('auth.User', related_name='middle_tasks')
    moreinfo = models.CharField(max_length=255, blank=True)

Task.objects.filter(middle_users__moreinfo="I'm filter!")
User.objects.filter(middle_tasks__moreinfo="I'm filter!")
User.objects.filter(tasks=some_task_instance)
User.objects.filter(tasks__int_field=5)