Money TransferWise Bank

A gem that calculates the exchange rate using available rates from the TransferWise Exchange Rate API.

TransferWise API

[
  /* 157 currencies */
  {
    "rate": 1.74145,
    "source": "USD",
    "target": "BGN",
    "time": "2019-06-05T17:48:33+0000"
  },
  {
    "rate": 1180.34,
    "source": "USD",
    "target": "KRW",
    "time": "2019-06-05T17:48:33+0000"
  },
  ...
]

Note that the TransferWise API is only available if you sign up for a free TransferWise account. See more information about their API in the TransferWise API Documentation

Features

supports 157 currencies
precision of rates up to 6 digits after point
uses fast and reliable JSON API
average response time < 400ms
supports caching currency rates
calculates every pair rate calculating inverse rate or using base currency rate
supports multiple server instances, thread safe

Installation

Add this line to your application's Gemfile:

gem 'money-transferwise-bank'

And then execute:

$ bundle

Or install it yourself as:

$ gem install money-transferwise-bank

Usage

# Minimal requirements
require 'money/bank/transferwise_bank'
mtwb = Money::Bank::TransferwiseBank.new
mtwb.access_key = 'your access_key from https://transferwise.com'

# Update rates (get new rates from remote if expired or access rates from cache)
mtwb.update_rates

# Force update rates from remote and store in cache
# mtwb.update_rates(true)

# (optional)
# Set the base currency for all rates. By default, USD is used.
mtwb.source = 'EUR'

# (optional)
# Set the seconds after than the current rates are automatically expired
# by default, they never expire, in this example 1 day.
mtwb.ttl_in_seconds = 86400

# (optional)
# Option to use the Sandbox version of the TransferWise API.
# By default, this is false and the live API is used.
mtwb.use_sandbox = true

# (optional)
# Option to raise an error on failure to connect to the API or parse
# the response. By default, this is true, but the ability to disable
# it is useful when developing without an active internet connection.
mtwb.raise_on_failure = false

# Define cache (string or pathname)
mtwb.cache = 'path/to/file/cache'

# Set money default bank to transferwise bank
Money.default_bank = mtwb

More methods

mtwb = Money::Bank::TransferwiseBank.new

# Returns the base currency set for all rates.
mtwb.source

# Expires rates if the expiration time is reached.
mtwb.expire_rates!

# Returns true if the expiration time is reached.
mtwb.expired?

# Get the API source url.
mtwb.source_url

# Get the rates timestamp of the last API request.
mtwb.rates_timestamp

# Get the rates timestamp of loaded rates in memory.
moxb.rates_mem_timestamp

How to exchange

# Exchange 1000 cents (10.0 USD) to EUR
Money.new(1000, 'USD').exchange_to('EUR')        # => #<Money fractional:89 currency:EUR>
Money.new(1000, 'USD').exchange_to('EUR').to_f   # => 8.9

# Format
Money.new(1000, 'USD').exchange_to('EUR').format # => €8.90

# Get the rate
Money.default_bank.get_rate('USD', 'CAD')        # => 0.9

See more on https://github.com/RubyMoney/money.

Using gem money-rails

You can also use it in Rails with the gem money-rails.

require 'money/bank/transferwise_bank'

MoneyRails.configure do |config|
  mtwb = Money::Bank::TransferwiseBank.new
  mtwb.access_key = 'your access_key from https://transferwise.com/product'
  mtwb.update_rates

  config.default_bank = mtwb
end

Cache

You can also provide a Proc as a cache to provide your own caching mechanism perhaps with Redis or just a thread safe Hash (global). For example:

mtwb.cache = Proc.new do |v|
  key = 'money:transferwise_bank'
  if v
    Thread.current[key] = v
  else
    Thread.current[key]
  end
end

Process

The gem fetches all rates in a cache with USD as base currency. It's possible to compute the rate between any of the currencies by calculating a pair rate using base USD rate.

Tests

You can place your own key on a file or environment variable named TEST_ACCESS_KEY and then run:

bundle exec rake

Refs

Other Implementations

Contributors

See github.com/mikelkew/money-transferwise-bank.
Inspired by github.com/phlegx/money-currencylayer-bank.

Contributing

Fork it ( https://github.com/[your-username]/money-transferwise-bank/fork )
Create your feature branch (git checkout -b my-new-feature)
Commit your changes (git commit -am 'Add some feature')
Push to the branch (git push origin my-new-feature)
Create a new Pull Request

License

The MIT License