price（）缺少1个必需的位置参数：'；自我'；在Django Rest框架中尝试计算价格时

我试图创建一个案例，当我调用OrderCreateAPI时，价格将自动计算并保存在数据库中，但我在postman中得到了这个错误

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')

此处，数量字段出现在OrderItem模型中，但价格出现在与产品模型相关的变量模型中，如下所示

我尝试过的事情：

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

我尝试删除price中的括号（），但得到了相同的错误

若我试着把price函数放在类模型中total_itel_price字段之前，它会说self是price括号中必需的，若我把self，=放在price中，我不知道该放在price中（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')

我的序列化程序：

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

订单序列化程序与上面的一样。它包括OrderItemSerializer，如图所示：

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']

订单总价计算更新。

这是我对total_price计算所做的，但是我没有在api响应中获得total_price字段，尽管没有错误

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price函数，我的OrderItem实例是OrderItems。有什么问题吗？？？

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"
    )

---

此代码最终用于OrderItem价格计算：

class OrderItem(models.Model): 
.....#fields same as above
    #total_item_price = models.PositiveIntegerField(blank=True,null=True,default=0)

    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')

    @property
    def price(self):
        total_item_price = self.quantity * self.order_variants.price
        return total_item_price

---

变体中有一个输入错误。此外，我应该使用order_变量而不是item.variants，因为item有许多变量，但用户只选择一个具有唯一价格的变量。

将order类中的价格函数定义为类方法。我已经用我尝试过的方法更新了我的问题。我已经将函数放在模型类中，但是它说从函数调用传递self。我还得把self=somthing放进去。但是我不知道该放什么。在你的问题中，你在类外定义了price函数。是的，但我尝试放在类内，并得到了相同的错误。你的

price（self）

方法应该在

OrderItem

类内。由于该方法在类之外，它希望传递

self

参数。并更改参数

default=price（）
total\u item\u price
inside
OrderItem
类的
default=price
属性。您不认为
price
方法应该在
OrderItem
类中，因为
Order
类没有
quantity
和
item
中所需的属性吗
price
method.Ah@Kishore，接得好我没查密码。让我更新答案。你好@VJMagar我厌倦了你的代码，但它是我的调用后api，我得到的reuslts是price=0。虽然没有错误，但已创建订单。我检查了物品的价格，它是500。@SarojPaudel你能试试更新代码吗？所以，总的物品价格不需要保存在数据库中？？不同的产品来自不同的供应商，所以我想我将来也需要总的商品价格。