从 Django 查询中的多对多关系中检索项目答案

【问题标题】：Retrieve items from Many-to-Many relationship in Django query从 Django 查询中的多对多关系中检索项目
【发布时间】：2020-03-03 05:27:40
【问题描述】：

模型.py

class SalesOrderItems(models.Model):
    item = models.ForeignKey(MasterItems, on_delete=models.CASCADE)
    item_quantity = models.IntegerField(default=0)


class SalesOrder(models.Model):

    delivery_method_choice = (('Full-Truck Load', 'Full-Truck Load'), ('Part-Truck Load', 'Part-Truck Load'))
    status_choices = (('On Hold', 'On Hold'),('Ready to Dispatch', 'Ready to Dispatch'),('Dispatched', 'Dispatched'))

    owner = models.ForeignKey(Teacher, on_delete=models.CASCADE, related_name='so_owner')
    client = models.ForeignKey(MasterClient, on_delete=models.CASCADE, related_name='so_client')
    reference_no = models.CharField(max_length=500, blank=True, null=True)
    date = models.DateField(default=datetime.date.today)
    shipment_date = models.DateField(default=datetime.date.today)
    delivery_method = models.CharField(max_length=500, default='Full-Truck Load', choices=delivery_method_choice)
    items = models.ManyToManyField(SalesOrderItems, related_name='items_so', blank=True, null=True)
    status = models.CharField(max_length=500, default='On Hold', choices=status_choices)
    origin = models.CharField(max_length=255)
    destination = models.CharField(max_length=255)

我想通过 django 查询检索特定销售订单的items

我尝试获取物品：

items = []

        for i in sales_orders:
            so = SalesOrder.objects.filter(pk=i)[0]
            print("items",so.items)

输出：

items classroom.SalesOrderItems.None

如何在特定的SalesOrder 中获取items 的列表？？

【问题讨论】：

标签： django orm django-queryset

【解决方案1】：

sales_orders = SalesOrder.objects.prefetch_related('items').filter(**sales_filter_here)

for sales_order in sales_orders:
    for sales_order_item in sales_order.items.all():
        print(sales_order_item)

【讨论】：

【解决方案2】：

这个查询对你有用

SalesOrder.objects.filter(id=1).values_list('items__item__item_name')

下面是我的简单 Masteritems 模型

class MasterItems(models.Model):
item_name = models.CharField(max_length=50)

def __str__(self):
    return self.item_name

通过这种方式，您将获得查询集中的每个项目名称。这是我的简单输出

<QuerySet [('rice',), ('pepsi',), ('Computer',)]>

【讨论】：