Awesome

eu_central_bank

Introduction

This gem downloads the exchange rates from the European Central Bank. You can calculate exchange rates with it. It is compatible with the money gem.

Installation

gem install eu_central_bank

In case you're using older ruby (< 2.1) you need nokogiri < 1.6.8, so add this to your Gemfile:

gem 'nokogiri', '1.6.8'

Dependencies

nokogiri
money

Usage

With the gem, you do not need to manually add exchange rates. Calling update_rates will download the rates from the European Central Bank. The API is the same as the money gem. Feel free to use Money objects with the bank.

require 'eu_central_bank'
eu_bank = EuCentralBank.new
Money.default_bank = eu_bank
money1 = Money.new(10)
money1.bank # eu_bank

# call this before calculating exchange rates
# this will download the rates from ECB
eu_bank.update_rates

# exchange 100 CAD to USD
# API is the same as the money gem
eu_bank.exchange(100, "CAD", "USD") # Money.new(80, "USD")
Money.us_dollar(100).exchange_to("CAD")  # Money.new(124, "CAD")

# using the new exchange_with method
eu_bank.exchange_with(Money.new(100, "CAD"), "USD") # Money.new(80, "USD")

For performance reasons, you may prefer to read from a file instead. Furthermore, ECB publishes their rates daily. It makes sense to save the rates in a file to read from. It also adds an updated_at field so that you can manage the update.

# cached location
cache = "/some/file/location/exchange_rates.xml"

# saves the rates in a specified location
eu_bank.save_rates(cache)

# reads the rates from the specified location
eu_bank.update_rates(cache)

if !eu_bank.rates_updated_at || eu_bank.rates_updated_at < Time.now - 1.days
  eu_bank.save_rates(cache)
  eu_bank.update_rates(cache)
end

# exchange 100 CAD to USD as usual
eu_bank.exchange_with(Money.new(100, "CAD"), "USD") # Money.new(80, "USD")

Note on Patches/Pull Requests

Fork the project.
Make your feature addition or bug fix.
Add tests for it. This is important so I don't break it in a future version unintentionally.
Commit, do not mess with rakefile, version, or history. (if you want to have your own version, that is fine but bump version in a commit by itself I can ignore when I pull)