money-distributed

👉 More or less maintained fork of the original gem. Use at your own risk ⚠️

Money gem extension for distributed systems

Money gem docs

example usage in conjunction with Open Exchange Rates, which offers a free API:

Our popular Free Plan provides hourly updates (with base currency USD) and up to 1,000 requests/month.

There is a gem available for OXR: money-open-exchange-rates

# config/initializers/money.rb

redis = Redis.new(url: ENV.fetch('REDIS_URL') { 'redis://localhost:6379/1' })
store = Money::Distributed::Storage.new(redis)

# we fetch rates from Open Exchange Rates:
oxr = Money::Bank::OpenExchangeRatesBank.new(store)
oxr.app_id = Rails.application.credentials.dig(:oxr, :api_key)

# fetch fresh rates if cache is empty so we don't boot the app without available rates
# we fetch those async to avoid the app crashing on boot due to an API error of OXR
MoneyUpdateRatesWorker.perform_async if oxr.rates.blank?

# to use the free plan of OXR, we must default to USD
oxr.source = 'USD'

Money.default_bank = oxr

The mentioned worker:

# app/workers/money_update_rates_worker.rb

class MoneyUpdateRatesWorker
  include Sidekiq::Worker

  def perform
    Money.default_bank.refresh_rates # pull from remote
    Money.default_bank.update_rates  # update cache
  end
end

You might want to set up a cron job to trigger this worker regularly. Set the schedule to a shorter time-window than the configured TTL of the exchange rates. This avoids, that rates are expired and have to be fetched from remote during a request.

You probably want to install the following gems:

# Gemfile

# payments
gem 'money'
gem 'money-distributed', git: 'git@github.com:swiknaba/money-distributed', branch: :master
gem 'money-open-exchange-rates'