显示外键值

Question

我的 models.py 看起来像这样：

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)

所以目前item我OrderItem模型中的字段显示模型中项目的标题和数量Item：

def __str__(self):

    return f"{self.quantity} of {self.item.title}"

ItemOneToOneField与Bike和连接Accessory。是否可以显示品牌和尺寸，Bike如果它被添加到OrderItem，brand_accessory如果Accessory被添加到OrderItem？

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

Answer 1

您可以使用hasattr检查您item是否需要 OneToOneFieldclass 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