为什么我收到错误：'QuerySet' 对象没有属性？

Question

我有3个模型

class Lease(CommonInfo):
    version = IntegerVersionField( )
    #amount  = models.DecimalField(max_digits=7, decimal_places=2)
    is_renewed = models.BooleanField(default=False)
    unit = models.ForeignKey(Unit)
    is_terminated = models.BooleanField(default=False)

class LeaseTerm(CommonInfo):
    version = IntegerVersionField( )
    start_period = models.ForeignKey(Period, related_name='start_period' )
    end_period = models.ForeignKey(Period, related_name='end_period')
    lease = models.ForeignKey(Lease)
    increase  = models.DecimalField(max_digits=7, decimal_places=2)
    amount  = models.DecimalField(max_digits=7, decimal_places=2)
    is_terminated = models.BooleanField(default=False)

    def clean(self):
    model = self.__class__
    if self.lease_id and (self.is_terminated == False) and model.objects.filter(lease=self.lease, is_active=True ).count() == 1:
        raise ValidationError('!Lease has a active condition already, Terminate prior to creation of new one'.format(self.lease))

class LeasePayment(CommonInfo):
    version = IntegerVersionField( )
    amount  = models.DecimalField(max_digits=7, decimal_places=2)
    leaseterm = models.ForeignKey(LeaseTerm)
    period_payed_for = models.DateTimeField()
    payment_date = models.DateTimeField()

（clean 方法只允许一个 LeaseTerm 处于活动状态且不被终止。）

在我看来，我希望看到为该 Lease 的活动 LeaseTerm 完成的所有付款

    lease = get_object_or_404(Lease, pk=lease_id)
    leaseterm = LeaseTerm.objects.filter(lease=lease, is_terminated =False, is_active = True )
    payment = leaseterm.leasepayment_set.all().order_by('payment_date')

但出现错误

'QuerySet' 对象没有属性 'leasepayment_set'

我做错了什么？

Answer 1

模型的实例LeaseTerm具有属性leasepayment_set，而不是模型的查询集LeaseTerm。您可以leasepayment_set通过获取这样的实例来访问。

1. get 代替 filter

   leaseterm = LeaseTerm.objects.get(lease=lease, ...)
   payment = leaseterm.leasepayment_set.all()
   

2. 循环查询集

   leaseterm = LeaseTerm.objects.filter(lease=lease, ...)
   for lt in leaseterm: # lt is an instance of LeaseTerm
       payment = lt.leasepayment_set.all()
   

3. （通过评论更新，感谢 Alasdair 和 Ingomar）从相关模型开始，它是更高效和优雅的查询表达式。

   LeasePayment.objects.filter(leaseterm__lease=lease)