显示外键值

Question

我的models.py是这样的：

class Order(models.Model):
    items = models.ManyToManyField(OrderItem)

class OrderItem(models.Model): (item in the cart)
   item = models.ForeignKey(Item, on_delete=models.CASCADE)

class Item(models.Model):
    title = models.CharField(max_length=100)
    price = models.FloatField()
    discount_price = models.FloatField(blank=True, null=True)
    label = models.ManyToManyField(Label, blank=True)
    slug = models.SlugField(unique=True)
    description = models.TextField()

class Bike(models.Model):
    item = models.OneToOneField(Item, on_delete=models.CASCADE)
    brand = models.ManyToManyField(Brand)
    size = models.ManyToManyField(Size, blank=True)

class Accessory(models.Model):
    item = models.OneToOneField(Item, on_delete=models.CASCADE)
    brand_accessory = models.ManyToManyField(BrandAccessory)

因此，目前我的OrderItem模型中的字段item显示了Item模型中项目的标题和数量：

def __str__(self):
    return f"{self.quantity} of {self.item.title}"

Item通过Bike和Accessory与OneToOneField相连。如果将Bike添加到OrderItem和brand_accessory，如果将Accessory添加到OrderItem，是否可以显示其品牌和大小

它看起来像{item.title} {item.title}(如果是自行车)> {bike.brand} {bike.size} (如果是附件)> {accessory.brand_accessory}

Answer 1

您可以使用hasattr检查您的item是否获得了所需的OneToOneField

class OrderItem(models.Model):

    ...

    def __str__(self):
        if hasattr(self.item, 'bike'):
            #get value you need like: self.item.bike.brand
        if hasattr(self.item, 'accessory'):
            #get value you need like: self.item.accessory.brand_accessory
        return #get values you need together