CODEWITHSUNDEEP
pythonpython-3.xcsv
user17025031
user17025031

Reputation: 3

Error: "TypeError: float() argument must be a string or a number, not 'NoneType'", but there is no 'NoneType'?

I am trying to print all the items but there is an error:

TypeError: float() argument must be a string or a number, not 'NoneType'

I have no clue why it is giving this error.

I am using float for price and int for quantity, because it initialises as a string by default, which will give another error because strings are not allowed as inputs for price and quantity.

import csv

class Item:
    pay_rate = 0.8 # The pay rate after 20% discount
    all = []
    def __init__(self, name: str, price: float, quantity=0):
        # Run validations to the received arguments
        assert price >= 0, f"Price {price} is below 0!"
        assert quantity >= 0, f"Price {price} is below 0!"


        # Assign to self object
        self.name = name
        self.price = price
        self.quantity = quantity


        # Actions to execute
        Item.all.append(self)


    def calculate_total_price(self):
        return self.price * self.quantity

    def apply_discount(self):
        self.price = self.price * self.pay_rate

    @classmethod
    def instantiate_from_csv(cls):
        with open('items.csv', 'r') as f:
            reader = csv.DictReader(f)
            items = list(reader)

        for item in items:

            Item(
                name=item.get('name'),
                price=float(item.get('price')),
                quantity=int(item.get('quantity')),
                )


    def __repr__(self):
        return f"Item('{self.name}', {self.price}, {self.quantity})"

Item.instantiate_from_csv()
print(Item.all)

CSV File:

name , price , quantity
"Phone" , 100 , 1
"Laptop" , 1000 , 3
"Cable" , 10 , 5
"Mouse" , 50 , 5
"Keyboard" , 75 , 5

Upvotes: 0

Views: 4591

Answers (1)

IGI
IGI

Reputation: 26

The true is the example csv data cause the key name of item is ' price ' (which with the space).

So item.get('price') will return default value None because it could not match ' price '.

Upvotes: 1

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