Python - 'NoneType' object is not subscriptable (A Small Program For Steam Item Price)

Question

So , i made this small program to update about the lowest_price of a specific item on steam market , it runs a loop and gets json response.

It works fine initially , displays the price , but after a while it shows the error.

The program code :

import json
import requests

def GetPrice () :

    response = requests.get ('https://steamcommunity.com/market/priceoverview/?appid=264710&currency=1&market_hash_name=Planet%204546B%20Postcard')

    json_data = {}
    json_data = json.loads (response.text)

    return json_data ["lowest_price"]

while True :

    print (GetPrice ())

Here is the output of the program :

$1.03
$1.03
$1.03
$1.03
$1.03
$1.03
$1.03
$1.03
$1.03
$1.03
$1.03
$1.03
$1.03
$1.03
$1.03
$1.03
$1.03
$1.03
$1.03
$1.03
$1.03
$1.03
Traceback (most recent call last):
  File "C:\Users\Admin\Desktop\item_price.py", line 16, in <module>
    print (GetPrice ())
  File "C:\Users\Admin\Desktop\item_price.py", line 12, in GetPrice
    return json_data ["lowest_price"]
TypeError: 'NoneType' object is not subscriptable
[Finished in 20.2s]

Answer 1

This error occurs when you are trying to index an object that is of type None (i.e: the object has no value).

Here your None object is your json_data variable, which means that json.loads (response.text) returns None.

You can avoid this error by adding an if statement that will check if the value is not None:

if json_data is not None:
    return json_data['lowest_price']
return None

Or with a try-except statement:

try:
    return json_data['lowest_price']
except Exception as e:
    return None    # or you can raise an exception if you want

Answer 2

You're experiencing this problem since you're making too many requests to the server really fast.

To be specific, the server replies with http error code 429

Consider waiting for a few seconds before sending successive requests.