Django ORM: count a subset of related items

Question

I am looking to find a way to annotate a queryset with the counts of a subset of related items. Below is a subset of my models:

class Person(models.Model):
    Name = models.CharField(max_length = 255)
    PracticeAttended = models.ManyToManyField('Practice',
                                              through = 'PracticeRecord')

class Club(models.Model):
    Name = models.CharField(max_length = 255)
    Slug = models.SlugField()
    Members = models.ManyToManyField('Person')

class PracticeRecord(PersonRecord):
    Person = models.ForeignKey(Person)
    Practice = models.ForeignKey(Practice)

class Practice(models.Model):
    Club = models.ForeignKey(Club, default = None, null = True)
    Date = models.DateField()

I'm looking to make a queryset which annotates the number of club specific practices attended by a person. I can already find the total number of practices by that person with a query of Person.objects.all().annotate(Count('PracticeRecord'))

However I would like someway to annotate the number of practices that a person attends for a specific club.

I would prefer something using the django ORM without having to resort to writing raw SQL.

Thanks.

Answer 1

I'm afraid that raw sql is the only option here. Anyway it's not that scary and hard to manage if you put it to model manager.