按属性值

Question

class Customer(models.Model):
    ...

class Order(models.Model):
    customer = models.ForeignKey(Customer)

    def __unicode__(self):
        return "<Order customer={}".format(self.customer.pk)

现在想象一下

>>> Order.objects.all()
[<Order customer=1>, <Order customer=1>, <Order customer=2>]

是否可以按分组方式获得结果？我可以用循环来做，但我正在寻找像＆＃34; group_by＆＃34;如果存在？我的后端是postgres

[[<Order customer=1>, <Order customer=1>], [<Order customer=2>]]

Order.objects.all().group_by('customer')

{AttributeError的}＆＃39; TreeQuerySet＆＃39;对象没有属性＆＃39; group_by＆＃39;

有循环：

orders = Order.objects.all()

data = {}
for order in orders:
    key = 'c_{}'.format(order.customer.pk)

    if key in data.keys():
         data[key].append(order)
    else:
         data[key] = [order]

>>> data.values()
[[<Order customer=1>, <Order customer=1>], [<Order customer=2>]]