Django QuerySet,基于每个数据的列/字段的最新条目过滤数据等于特定值

时间:2018-09-07 02:26:29

标签: django django-models django-queryset django-orm

#models.py
class Orders(models.Model):
    orderid = models.IntegerField(db_column='orderID', primary_key=True) 
    createdate = models.DateField(db_column='createDate', blank=True, null=True) 
    pickupdate = models.DateField(db_column='pickupDate', blank=True, null=True)  
    returndate = models.DateField(db_column='returnDate', blank=True, null=True)  
    pickupstore = models.ForeignKey(Branch, models.DO_NOTHING, db_column='pickupStore', blank=True, null=True,related_name = 'pickupstore')  
    returnstore = models.ForeignKey(Branch, models.DO_NOTHING, db_column='returnStore', blank=True, null=True,related_name = 'returnstore') 
    rentedvehicle = models.ForeignKey('Vehicles', models.DO_NOTHING, db_column='rentedVehicle', blank=True, null=True)  
    customer = models.ForeignKey(Customer, models.DO_NOTHING, db_column='customer', blank=True, null=True)


class Vehicles(models.Model):
    vehicleid = models.IntegerField(db_column='vehicleID', primary_key=True)  
    make = models.CharField(max_length=45, blank=True, null=True)
    model = models.CharField(max_length=45, blank=True, null=True)
    series = models.CharField(max_length=45, blank=True, null=True)

订单模型具有外键租用的车辆,指的是车辆模型

我已根据取货商店的状态过滤了数据,例如在特定状态下从商店取车的车辆列表

Vehicles.objects.filter(orders__pickupstore__state = request.POST['state'])

我希望能够过滤上面过滤的数据,这样我就可以获得在特定状态下从商店取回的车辆的列表,其最新输入在Orders模型中具有returnstore__state ==特定状态

所以基本上,我想实现这一点:

Vehicles.objects.filter(orders__pickupstore__state = request.POST['state']).filter(the latest entry returnstore state =request.POST['state'])

1 个答案:

答案 0 :(得分:1)

许多可能的解决方案。最佳取决于您的Django版本(1.11或更高版本?)。这是一种可能的解决方案:

from django.db.models import Max, F

Vehicles.objects.filter(orders__pickupstore__state = request.POST['state']).annotate(max_date=Max('orders__returndate')).filter(orders__return_date=F('max_date')).filter(orders__state = request.POST['state'])

这里发生的事情是,我们要确定最近的退货日期,然后过滤订单以仅包括最新的退货日期,然后根据最新订单的状态过滤车辆。