required functionality:

• Get exchange rates from one into one or more currencies
• Get value converted from one into one or more currencies
• Give the best rate and date over the last 7 days for a given currency pair

This Gem is build on top of the money gem. It implements a new bank (Money::Bank) CurrencyLayerBank, which fetches current exchange rates from the currencylayer API.

Implemented APIs

• https://currencylayer.com/documentation

Locally add the API key to ENV: export CURRENCYLAYER_API_KEY=YOUR_PRIVATE_KEY

build & install GEM locally

if previously built, remove gem file: rm cringle_money-0.0.3.gem

gem build cringle_money.gemspec
gem install cringle_money-0.0.3.gem

Run via commandline:

irb
require 'cringle_money'

this should return: => true

now you can define any currencies using iso_codes:

from_currency = Money::Currency.wrap(:eur)
to_currency = Money::Currency.wrap(:usd)
to_currency2 = Money::Currency.wrap(:aud)
to_currencies = [to_currency, to_currency2]

define a date for which you wish to retrieve exchange rates

exchange_date = Date.new(2018, 5, 20)

Get exchange rates:

CringleMoney.get_rates(from_currency, to_currencies, date: exchange_date)

which will return:

=> {"USD"=>1.177026, "AUD"=>1.564153}

Get the best rate for the past 7 days via:

CringleMoney.best_rate(from_currency, to_currency)

which will return an array with one Date object and an exchange rate

=> [#<Date: 2018-05-15 ((2458254j,0s,0n),+0s,2299161j)>, "1.182595"]

Generate a CringleMoney object for any amount, e.g. 10 EUR (= 1.000 cents) and exchange it into any other currencies:

m = CringleMoney.new(1_000, 'EUR', date: exchange_date)
m.exchange_to(to_currencies)

which will return an array of CringleMoney objects (= Money object with an exchange_date property)

=> [#<CringleMoney fractional:1177 currency:USD>, #<CringleMoney fractional:1564 currency:AUD>]

Note: CringleMoney.fractional returns the value given in the currency's smallest unit, which is cents for EUR. You can easily format it using Money's build in methods: money.fractional.to_f / money.currency.subunit_to_unit

will result in 11.77 USD