Question

我有2个模特

class ShipmentBagSealMapping(models.Model):
    bag_seal = models.CharField(max_length = 255)
    status = models.CharField(max_length = 255, default = 'open')
    time = models.DateTimeField( auto_now_add = True, db_index = True)
    shipment_id = models.ForeignKey('Shipment', related_name = 'bags')



class Shipment(models.Model):
    job_id = models.CharField(max_length = 255)
    time = models.DateTimeField( auto_now_add = True, db_index = True)

我想写一个 JOIN 查询，它告诉我ShipmentBagSealMapping中status = close的记录数和Shipment的时间范围{{1 }}

这里'我尝试过：

[start_time and end_time]

但它引发了一个错误说： -

total_bags = ShipmentBagSealMapping.objects.filter(shipments__time__range = [start_time,end_time],status='close').values('bag_seal').distinct().count()

我该怎么做？

Answer 1

这应该这样做：

total_bags = ShipmentBagSealMapping.objects.filter(shipment_id__time__range = [start_time,end_time],status='close').values('bag_seal').distinct().count()

看到您已将该字段定义为shipment_id而非shipments

Answer 2

Django会自动在你的ForeignKey中添加_id，所以做一些像这样的改变可能有帮助

class ShipmentBagSealMapping(model.Model):
bag_seal = models.CharField(max_length = 255)
status = models.CharField(max_length = 255 )
time = models.DateTimeField( auto_now_add = True)
shipments = models.ForeignKey('Shipment', related_name = 'bags')

Django ORM JOIN查询

2 个答案: