Question

This is a python question.

Start with this program,

import json
from urllib import request


def main():
    to_continue = 'Yes'
    while to_continue == 'yes' or to_continue == 'Yes':
        currency_code = input("Enter currency code: ").upper()
        dollars = int(input("Enter number of dollar you want to convert: "))
        # calling the exchange_rates function
        data = get_exchange_rates()
        if currency_code in data["rates"].keys():
            currency = data["rates"][currency_code]
            # printing the the currency value  by multiplying the dollars amount.
            print("The value is:", str(currency * dollars))
        else:
            print("Error: the conversion can't be done it")
        to_continue = input(f"would you like to continue, enter 'Yes' or 'No' ")


# You do not need to modify any code below here.

def get_exchange_rates():
    """" Connect to the exchangeratesapi.io server and request the latest exchange rates,
    relative to US Dollars.  Return the response as a dictionary. """

    url = 'https://api.exchangeratesapi.io/latest?base=USD'

    try:  # Attempt to connect to the exchangeratesapi server
        response = request.urlopen(url).read()   # and get the server's response
        data = json.loads(response)   # convert the response to a Python dictionry
        return data  # return the dictionary
    except:  # this code runs if there's any error fetching data.
        # It returns some example data, that has the same structure as real data, to use instead
        # So it's no problem if you don't have an internet connection or there exchange rates api server is down.
        #print('There was an error fetching real data. Perhaps you are offline? Returning example data.')
        return example_exchange_rates()


def example_exchange_rates():
    """ In case the exchangeratesapi.io is not available, the program will use this example data.
     This data has the same structure as real data, so your program doesn't need to worry if real data
     or example data is used. """
    example_data = {
       "base": "USD",
       "date": "2019-01-30",
       "rates": {
          "ISK": 119.8705048561,
          "CAD": 1.3221629189,
          "MXN": 19.0960713973,
          "CHF": 0.9977250853,
          "AUD": 1.3898853793,
          "CNY": 6.7168606177,
          "GBP": 0.7642050923,
          "USD": 1.0,
          "SEK": 9.0859217779,
          "NOK": 8.4817569341,
          "TRY": 5.2750021874,
          "IDR": 14130.0026249016,
          "ZAR": 13.6043398373,
          "HRK": 6.4953189255,
          "EUR": 0.8749671887,
          "HKD": 7.8451308076,
          "ILS": 3.6677749584,
          "NZD": 1.4632076297,
          "MYR": 4.1057835331,
          "JPY": 109.4408959664,
          "CZK": 22.5759034036,
          "SGD": 1.3510368361,
          "RUB": 65.9388397935,
          "RON": 4.1605564791,
          "HUF": 276.9533642488,
          "BGN": 1.7112608277,
          "INR": 71.1794557704,
          "KRW": 1118.1905678537,
          "DKK": 6.5314550704,
          "THB": 31.3798232566,
          "PHP": 52.3002887392,
          "PLN": 3.7540467232,
          "BRL": 3.7091609065
       }
    }

    return example_data

main()

This program fetches data every time the user wants to make a conversion. But, the exchange rates don't change very fast, so the program may fetch the same data over and over again.

For this question, shelve the exchange rates to a file with today's date in the name. When the program loads, if there is a file with today's date in the name, then read the exchange rate data dictionary from that file and use it in your program.

If there is no shelf file with today's date in the name, then call the get_exchange_rates() function to get the most recent data from exchangeratesapi.io.

Storing recently used data to save fetching data from a store is called caching, and it's common in many areas of computing.

Answer 1

I have attached the code below. If you have any problem, feel free to discuss.

Program Screenshot:

Sample Output:

Program Code to copy:

import json
from urllib import request
from datetime import datetime

def main():
    to_continue = 'Yes'
    while to_continue == 'yes' or to_continue == 'Yes':
        currency_code = input("Enter currency code: ").upper()
        dollars = int(input("Enter number of dollar you want to convert: "))
        # calling the exchange_rates function
        # we will store latest exchange rates in a file called exchange_rates.json
        cachefilename = "exchange_rates.json"
        try:
            with open(cachefilename) as f:
                data = json.load(f)
                #match current data date
                if datetime.utcnow().date().isoformat() != data['date']:
                    data = get_exchange_rates()
        except FileNotFoundError:
            data = get_exchange_rates()
        if currency_code in data["rates"].keys():
            currency = data["rates"][currency_code]
            # printing the the currency value by multiplying the dollars amount.
            print("The value is:", str(currency * dollars))
        else:
            print("Error: the conversion can't be done it")
        to_continue = input(f"would you like to continue, enter 'Yes' or 'No' ")
    ##dump file
    with open(cachefilename , 'w') as f:
        json.dump(data , f)

# You do not need to modify any code below here.

def get_exchange_rates():
    """" Connect to the exchangeratesapi.io server and request the latest exchange rates,
    relative to US Dollars. Return the response as a dictionary. """

    url = 'https://api.exchangeratesapi.io/latest?base=USD'

    try: # Attempt to connect to the exchangeratesapi server
        response = request.urlopen(url).read()   # and get the server's response
        data = json.loads(response)   # convert the response to a Python dictionry
        return data # return the dictionary
    except: # this code runs if there's any error fetching data.
        # It returns some example data, that has the same structure as real data, to use instead
        # So it's no problem if you don't have an internet connection or there exchange rates api server is down.
        #print('There was an error fetching real data. Perhaps you are offline? Returning example data.')
        return example_exchange_rates()

def example_exchange_rates():
    """ In case the exchangeratesapi.io is not available, the program will use this example data.
     This data has the same structure as real data, so your program doesn't need to worry if real data
     or example data is used. """
    example_data = {
       "base": "USD",
       "date": "2019-01-30",
       "rates": {
          "ISK": 119.8705048561,
          "CAD": 1.3221629189,
          "MXN": 19.0960713973,
          "CHF": 0.9977250853,
          "AUD": 1.3898853793,
          "CNY": 6.7168606177,
          "GBP": 0.7642050923,
          "USD": 1.0,
          "SEK": 9.0859217779,
          "NOK": 8.4817569341,
          "TRY": 5.2750021874,
          "IDR": 14130.0026249016,
          "ZAR": 13.6043398373,
          "HRK": 6.4953189255,
          "EUR": 0.8749671887,
          "HKD": 7.8451308076,
          "ILS": 3.6677749584,
          "NZD": 1.4632076297,
          "MYR": 4.1057835331,
          "JPY": 109.4408959664,
          "CZK": 22.5759034036,
          "SGD": 1.3510368361,
          "RUB": 65.9388397935,
          "RON": 4.1605564791,
          "HUF": 276.9533642488,
          "BGN": 1.7112608277,
          "INR": 71.1794557704,
          "KRW": 1118.1905678537,
          "DKK": 6.5314550704,
          "THB": 31.3798232566,
          "PHP": 52.3002887392,
          "PLN": 3.7540467232,
          "BRL": 3.7091609065
       }
    }

    return example_data

main()