django - price() 在尝试计算 Django Rest Framework 中的价格时缺少 1 个必需的位置参数:“self”
问题描述
我正在尝试创建一个案例,当我调用 order create api 时,价格将自行计算并保存在数据库中,但我在邮递员中收到此错误。
错误:price() 缺少 1 个必需的位置参数:'self
我的模型:
class Order(models.Model):
user = models.ForeignKey(User, on_delete=models.CASCADE, blank=True)
ordered_date = models.DateTimeField(auto_now_add=True)
ordered = models.BooleanField(default=False)
total_price = models.CharField(max_length=50,blank=True,null=True)
#billing_details = models.OneToOneField('BillingDetails',on_delete=models.CASCADE,null=True,blank=True,related_name="order")
def __str__(self):
return self.user.email
def price(self):
total_item_price = self.quantity * self.item.varaints.price
return total_item_price
class OrderItem(models.Model):
#user = models.ForeignKey(User,on_delete=models.CASCADE, blank=True
#orderItem_ID = models.UUIDField(max_length=12, editable=False,default=str(uuid.uuid4()))
orderItem_ID = models.CharField(max_length=12, editable=False, default=id_generator)
order = models.ForeignKey(Order,on_delete=models.CASCADE, blank=True,null=True,related_name='order_items')
item = models.ForeignKey(Product, on_delete=models.CASCADE,blank=True, null=True)
order_variants = models.ForeignKey(Variants, on_delete=models.CASCADE,blank=True,null=True)
quantity = models.IntegerField(default=1)
total_item_price = models.PositiveIntegerField(blank=True,null=True,default=price())
ORDER_STATUS = (
('To_Ship', 'To Ship',),
('Shipped', 'Shipped',),
('Delivered', 'Delivered',),
('Cancelled', 'Cancelled',),
)
order_item_status = models.CharField(max_length=50,choices=ORDER_STATUS,default='To_Ship')
这里的数量字段存在于 OrderItem 模型本身中,但价格存在于与 Product 模型相关的 Variant 模型中,就像这样。
我尝试过的事情:
- 我尝试删除价格中的括号 (),但得到了同样的错误。
- 如果我尝试在 total_itel_price 字段之前将 price 函数放入类模型中,它会在 price 括号内表示 self 是必需的,如果我放入 self,= 是必需的,我不知道放入 price(self=??)
其他型号:
Class Variants(models.Model):
...#other fields
price = models.DecimalField(decimal_places=2, max_digits=20,default=500)
Class Product(models.Model):
...#other fields
variants = models.ManyToManyField(Variants,related_name='products')
我的序列化器:
class OrderSerializer(serializers.ModelSerializer):
billing_details = BillingDetailsSerializer()
order_items = OrderItemSerializer(many=True)
user = serializers.PrimaryKeyRelatedField(read_only=True, default=serializers.CurrentUserDefault())
class Meta:
model = Order
fields = ['id','user','ordered_date','order_status', 'ordered', 'order_items', 'total_price','billing_details']
# depth = 1
def create(self, validated_data):
user = self.context['request'].user
if not user.is_seller:
order_items = validated_data.pop('order_items')
billing_details = validated_data.pop('billing_details')
order = Order.objects.create(user=user,**validated_data)
BillingDetails.objects.create(user=user,order=order,**billing_details)
for order_items in order_items:
OrderItem.objects.create(order=order,**order_items)
else:
raise serializers.ValidationError("This is not a customer account.Please login as customer.")
更新代码:
class OrderItem(models.Model):
#total_item_price = models.PositiveIntegerField(blank=True,null=True,default=0) #commented out this field other fields are same as above
order_item_status = models.CharField(max_length=50,choices=ORDER_STATUS,default='To_Ship')
@property
def price(self):
return self.quantity * self.item.varaints.price
class OrderItemSerializer(serializers.ModelSerializer):
order = serializers.PrimaryKeyRelatedField(read_only=True)
price = serializers.ReadOnlyField()
class Meta:
model = OrderItem
fields = ['id','order','orderItem_ID','item','order_variants', 'quantity','order_item_status','price']
# depth = 1
Order Serializer 就像上面一样。它包括 OrderItemSerializer,如下所示:
class OrderSerializer(serializers.ModelSerializer):
billing_details = BillingDetailsSerializer()
order_items = OrderItemSerializer(many=True)
user = serializers.PrimaryKeyRelatedField(read_only=True, default=serializers.CurrentUserDefault())
class Meta:
model = Order
fields = ['id','user','ordered_date','order_status', 'ordered', 'order_items', 'total_price','billing_details']
更新 Order total_price 计算。
这是我为 total_price 计算所做的,但我没有在 api 响应中得到 total_price 字段,但没有错误。
class Order(models.Model):
.....#same fields as above
@property
def total_order_price(self):
return sum([_.price for _ in self.order_items_set.all()])
我在 OrderItem 模型中使用了价格函数,我的 OrderItem 实例是 order_items。什么问题??
解决方案
试试这个
class Order(models.Model):
"""Stores the details of the order"""
user: User = models.ForeignKey(User, on_delete=models.CASCADE, blank=True)
ordered_date = models.DateTimeField(auto_now_add=True)
ordered = models.BooleanField(default=False)
# billing_details = models.OneToOneField('BillingDetails',on_delete=models.CASCADE,null=True,blank=True,related_name="order")
def __str__(self) -> str:
return self.user.email
@property
def total_price(self) -> int:
"""
Dropped the total price field and created it as property
This is not the best practice, I am leaving that as practice for you :)
"""
return sum([_.total_item_price for _ in self.orderitem_set.all()])
class OrderItem(models.Model):
"""Order Item stores the details of the each order item"""
orderItem_ID: str = models.CharField(
max_length=12, editable=False, default=id_generator
)
order: Order = models.ForeignKey(
Order,
on_delete=models.CASCADE,
blank=True,
null=True,
related_name="order_items",
)
item: Product = models.ForeignKey(
Product, on_delete=models.CASCADE, blank=True, null=True
)
order_variants: Variants = models.ForeignKey(
Variants, on_delete=models.CASCADE, blank=True, null=True
)
quantity: int = models.IntegerField(default=1)
price = models.PositiveIntegerField()
@property
def total_item_price(self):
"""
Calculates total item price for the item
Here you can also add additional logics such as
taxes per item etc
"""
return self.price * self.quantity
ORDER_STATUS = (
("To_Ship", "To Ship"),
("Shipped", "Shipped"),
("Delivered", "Delivered"),
("Cancelled", "Cancelled"),
)
order_item_status = models.CharField(
max_length=50, choices=ORDER_STATUS, default="To_Ship"
)
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