A simple client for this library and Django.

[Sigularusrex]

I thought I'd share my client implementation for using this library. It's quite specific to my needs at the moment, but with a little discussion, maybe it can be improved.

from currency_converter import CurrencyConverter, ECB_URL, RateNotFoundError
import os.path as op
import urllib.request
import zipfile

from settings import STATIC_ROOT, STATIC_URL

ZIP_FILE_PATH = f"{STATIC_ROOT}/eurofxref-hist.zip"
CSV_FILE_PATH = f"{STATIC_ROOT}/eurofxref-hist.csv"


class CurrencyConverterClient:
    def __init__(self):
        try:
            self.currency_converter = CurrencyConverter(currency_file=CSV_FILE_PATH,
                                                        decimal=True,
                                                        fallback_on_missing_rate=True)
        except FileNotFoundError as e:
            self.fetch_new_rates()

    def convert(self, amount, from_currency, to_currency, conversion_date, attempt_to_fetch_new_rates=True):
        try:
            result = self.currency_converter.convert(amount, from_currency, to_currency, conversion_date)
            return round(result, 2)
        except RateNotFoundError as e:
            if attempt_to_fetch_new_rates:
                # Can't find the rate? re-fetch all
                # data and reassign the converter (slower, but safer)
                self.fetch_new_rates(ECB_URL)
                return self.convert(amount, from_currency, to_currency, conversion_date, False)
        except ValueError as e:
            return str(e)

    def list_available_currencies(self):
        result = self.currency_converter.currencies
        return result

    # New currency conversion data is loaded at 2pm CET each day. So we will want to call this function daily
    # to ensure we can convert all currencies at any date from 1999 to today. Alternatively, this will be called
    # when RateNotFoundError is raised.
    def fetch_new_rates(self):
        try:
            urllib.request.urlretrieve(ECB_URL, ZIP_FILE_PATH)
        except Exception as e:
            raise e
        try:
            with zipfile.ZipFile(ZIP_FILE_PATH, 'r') as zip_ref:
                zip_ref.extractall(STATIC_ROOT)
        except Exception as e:
            raise f"Error extracting {ZIP_FILE_PATH}: {str(e)}"

        # Re-initialize the currency converter with the new data
        self.currency_converter = CurrencyConverter(currency_file=CSV_FILE_PATH,
                                                    decimal=True,
                                                    fallback_on_missing_rate=True)
        return True

[Sigularusrex]

Here are a few basic tests in case you want to try it in your project:

import decimal
import datetime


@pytest.fixture
def currency_converter_client():
    return CurrencyConverterClient()


def test_convert(currency_converter_client):
    result = currency_converter_client.convert(100, "USD", "EUR", datetime.date(2020, 1, 1))
    assert isinstance(result, decimal.Decimal)


def test_convert_invalid_currency(currency_converter_client):
    result = currency_converter_client.convert(100, "XYZ", "EUR", datetime.date(2020, 1, 1))
    assert isinstance(result, str)


def test_list_available_currencies(currency_converter_client):
    result = currency_converter_client.list_available_currencies()
    assert isinstance(result, set)
    assert "USD" in result
    assert "EUR" in result


def test_fetch_new_rates(currency_converter_client):
    result = currency_converter_client.fetch_new_rates()
    assert result is True

[alexprengere]

For the record, here is the code I use to make sure I always have the latest rates (it is in the README as well). It downloads the data for the day, unless it has already been downloaded:

import os.path as op
import urllib.request
from datetime import date

from currency_converter import ECB_URL, CurrencyConverter

filename = f"ecb_{date.today():%Y%m%d}.zip"
if not op.isfile(filename):
    urllib.request.urlretrieve(ECB_URL, filename)
c = CurrencyConverter(filename)