Python “非类型”对象没有属性“价格”

models.py

class ShopCart(models.Model):
    user = models.ForeignKey(User, on_delete=models.SET_NULL, null=True)
    Food = models.ForeignKey(food, on_delete=models.SET_NULL, null=True)
    quantity = models.IntegerField()

    def __str__(self):
        return self.Food

    @property
    def amount(self):
        return (self.quantity * self.Food.price) #adminde göstermek için tutar

    @property
    def price(self):
        return (self.Food.price)

管理员

class food(models.Model):
    STATUS = (
        ('True', 'Evet'),
        ('False', 'Hayır'),
    )
    category = models.ForeignKey(Category, on_delete=models.CASCADE) #Category modeli ile ilişkili
    title = models.CharField(max_length=150)
    keywords = models.CharField(blank=True,max_length=255)
    description = models.CharField(blank=True,max_length=255)
    image = models.ImageField(blank=True, upload_to='images/')
    price = models.FloatField()
    amount = models.IntegerField() #miktar
    detail = RichTextUploadingField()
    slug = models.SlugField(null=False, unique=True)
    status = models.CharField(max_length=10, choices=STATUS)
    created_at = models.DateTimeField(auto_now_add=True)
    update_at = models.DateTimeField(auto_now=True)

    def __str__(self):
        return self.title

---

我在尝试输入admin.py时出错。你们能帮帮我吗？

之所以失败是因为self.Food可以为空，所以没有，在这种情况下，self.Food.price当然失败了

您可以防范None，例如，在这种情况下返回None：

class ShopCartAdmin(admin.ModelAdmin):
    list_display = ['user','Food','price','quantity','amount']
    list_filter = ['user']

admin.site.register(ShopCart,ShopCartAdmin)

---

也就是说，最好将字段设置为不可空，并查看数据库，其中由于某种原因，食品列确实为空。

self.Food可以为空，因此没有，然后它就没有价格。那么我该怎么办呢？

@property
def amount(self):
    if self.Food_id is None:
        return `None`
    return self.quantity * self.Food.price

@property
def price(self):
    if `self.Food_id is not None:
        return self.Food.price