KeyError: 'rates' - Json from fixer.io - Python

Question

I have this code:

def getExchangeRates():
    rates = []
    response = urlopen('my_key')
    data = response.read()
    rdata = json.loads(data.decode(), parse_float=float) 

    rates.append( rdata['rates']['USD'] )
    rates.append( rdata['rates']['GBP'] )
    rates.append( rdata['rates']['HKD'] )
    rates.append( rdata['rates']['AUD'] )
    return rates

This code was working, but now I get the following error:

Traceback (most recent call last):
File "/home/kristian/.virtualenvs/usio_flask/lib/python3.4/site-packages/flask/app.py", line 2292, in wsgi_app
response = self.full_dispatch_request()
File "/home/kristian/.virtualenvs/usio_flask/lib/python3.4/site-packages/flask/app.py", line 1815, in full_dispatch_request
rv = self.handle_user_exception(e)
File "/home/kristian/.virtualenvs/usio_flask/lib/python3.4/site-packages/flask/app.py", line 1718, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "/home/kristian/.virtualenvs/usio_flask/lib/python3.4/site-packages/flask/_compat.py", line 35, in reraise
raise value
File "/home/kristian/.virtualenvs/usio_flask/lib/python3.4/site-packages/flask/app.py", line 1813, in full_dispatch_request
rv = self.dispatch_request()
File "/home/kristian/.virtualenvs/usio_flask/lib/python3.4/site-packages/flask/app.py", line 1799, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "app/app.py", line 30, in index
rates = getExchangeRates()
File "app/app.py", line 22, in getExchangeRates
rates.append( rdata['rates']['USD'] )
KeyError: 'rates'

The weird thing, is that the rates is being initialized here:

rates = []

Any ideas?

Answer 1

The KeyError is because rates is not a key in the rdata. When looking up a key on a dict, it is always a good idea to catch KeyError or use get which allows you to provide a default value in case the key is not found. The code below illustrates both methods:

rates_from_rdata = rdata.get('rates', {})
for rate_symbol in ['USD', 'GBP', 'HKD', 'AUD']:
    try:
        rates.append(rates_from_rdata[rate_symbol])
    except KeyError:
        print ('rate for {} not found in rdata'.format(rate_symbol))
        pass

Answer 2

Do as follows

res = requests.get("http://data.fixer.io/api/latest?access_key=0cf7e4582cfe4e7de960de93c6c4bf9a")
data=res.json()
print(data)

if it has rates in the dictionary in single quotes use single quotes (what you are doing) else if "rates" is in double quotation mark use double quotation while appending. Also, check your subscription plan if it is free it does not support USD.