Django用空的ManyToManyField选择对象

Question

考虑到以下型号，了解一个家庭，如何选择没有买家的孩子？

class Family...

class Kid(models.Model):
    name = models.CharField(max_length=255)
    family = models.ForeignKey(Family)
    buyer = models.ManyToManyField(Buyer, blank=True, null=True)

family = get_object_or_404(Family, pk=1)
for_sale = family.kid_set.filter(buyer... this screws my child trade business

Answer 1

family.kid_set.filter(buyer__isnull=True)应该有用。

Answer 2

@ piquadrat的answer是正确的。你也可以 做：

for_sale = Kid.objects.filter(family__pk = 1, buyer = None)

这使您可以避免单独的查询来查找Family实例。