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我有2个模型。 serviceinvoice和invoiceitems。 invoiceitems模型通过外键链接到serviceinvoice。Django:如何获得有关单行的所有行的总和
现在对于单张发票,我如何获得总折扣金额? 注释不起作用,因为它仅适用于单行。 Models.py
class serviceinvoice(models.Model):
user=models.ForeignKey(settings.AUTH_USER_MODEL,related_name='invoice')
invoice_number=models.CharField(max_length=100)
invoice_date = models.DateField()
class serviceinvoiceitems(models.Model):
user=models.ForeignKey(settings.AUTH_USER_MODEL,related_name='serviceinvoiceitem')
company=models.ForeignKey(Organisation,related_name='sitemcomp')
invoice_number=models.ForeignKey(serviceinvoice,related_name='serviceitems1')
discount = models.BooleanField(default=False)
discount_amount = models.FloatField(null=True,blank=True,default=0)
Amount=models.FloatField()
discription=models.CharField(max_length=500,blank=True,null=True)
我试图在视图:
invoice_detailmain = serviceinvoice.objects.get(pk=pk)
dis_value_total = Sum('invoice_detailmain__serviceitems1__discount_amount')
它不给DISCOUNT_AMOUNT的总和。 什么是解决方案以及如何在模板中显示它?