Function returns None- Python

Question

I call an exchange API. When I try to put it as a function, it returns None:

def getCurrentExchange(source, target):
    """The function takes the source - source and target currency - target and extract the rate as of now"""
    url = 'https://api.exchangerate.host/convert?from=source&to=target'
    response = requests.get(url)
    data = response.json()
    xchng = data['result']
    return xchng 
print(getCurrentExchange("EUR", "USD"))

When I call the API without wrapping it as a function, I get the rate:

url = 'https://api.exchangerate.host/convert?from=USD&to=EUR'
response = requests.get(url)
data = response.json()
data['result']

What am I doing wrong?

You need to add the line `return xchng` at the end of your function. Any function without a `return` statement will return `None` — C_Z_, Jan 11 '23 at 16:39
You aren't returning anything from your function, just printing. — takendarkk, Jan 11 '23 at 16:39
Unfortunately, even if I add return xchng and then, wrap getCurrentExchange("EUR", "USD") to print(getCurrentExchange("EUR", "USD")), I would still get None — eponkratova, Jan 11 '23 at 16:43
@eponkratova Update your code with a return in your function and request a re-open since it does not solve your issue — Jib, Jan 11 '23 at 16:48
I think it has sth to do with the type - the rate is float. When I use the function, the returned type is NoneType , when I just call the API, the type is float. — eponkratova, Jan 11 '23 at 16:56
@eponkratova This has to do with the URL you use in the function. You should use built-in string `format` to install value in your url: `"my_api_url = "https://api.exchangerate.host/convert?from={}&to={}".format(source, target)`. This will solve your issue — Jib, Jan 11 '23 at 17:00
And indeed, it did solve the problem! Thank you, @Jib. I guess we cannot do anything with the closed status — eponkratova, Jan 11 '23 at 17:02

samusa · Answer 1 · 2023-01-11T16:45:20.570

0

you need a return value.

def getCurrentExchange(source, target):
    """The function takes the source - source and target currency - target and extract the rate as of now"""
    url = f'https://api.exchangerate.host/convert?from={source}&to={target}'
    response = requests.get(url)
    data = response.json()
    return data['result']
getCurrentExchange("EUR", "USD")

edited Jan 11 '23 at 16:45

answered Jan 11 '23 at 16:40

samusa

449
2
11

No, if I use def getCurrentExchange(source, target): """The function takes the source - source and target currency - target and extract the rate as of now""" url = 'https://api.exchangerate.host/convert?from=source&to=target' response = requests.get(url) data = response.json() xchng = data['result'] return xchng print(getCurrentExchange("EUR", "USD")) it still returns None – eponkratova Jan 11 '23 at 16:42
with f-strings you can fill your values into the url – samusa Jan 11 '23 at 16:47

Function returns None- Python

1 Answers1