Filtering based on .count() of a forgein key field in Django querysets

问题

So I have some Django 1.3 models like this:

class Type(models.Model):
  is_bulk = models.BooleanField()

class Component(models.Model):
  parent = models.ForeignKey(Type)

Some Type's have 0 Component's, some have 1, or 2, etc. How do I write a QuerySet that filters all Type's that have > 0 Components. i.e. exclude Types that have 0 Components?

回答1:

from django.db.models import Count
Type.objects.annotate(component_count=Count('component')).exclude(component_count=0)

来源：https://stackoverflow.com/questions/8068771/filtering-based-on-count-of-a-forgein-key-field-in-django-querysets