Rails plugin to retrieve and store the currency rates daily to integrate
with the money-rails
gem.
Storing the current currency rates in the database using ActiveCurrency provides the following advantages:
- Lets you query for the currency rate you actually used in your application at any given time.
- Does not need to call an API to get the rates when starting or restarting your web server.
- Does not depend on the file system to store cached rates.
- Choose how often you want to update the currency rates (daily for example).
- Your users do not suffer the cost of making calls to the bank rates API.
- Your app does not go down when the bank rates API does.
To fetch the current rate it uses your application cache instead of making a call to the database.
Store the current rate regularly by calling in a scheduled job (using something
like sidekiq-scheduler
, whenever
, or active_scheduler
) with the currencies
you want to store:
ActiveCurrency::AddRates.call(%w[EUR USD])
You can then exchange money by using the Money gem helpers:
10.to_money('EUR').exchange_to('USD').cents
If you need to look up the previous currency rates:
ActiveCurrency::Rate.value_for('EUR', 'USD', 1.month.ago)
# => 1.151
ActiveCurrency::Rate.where(from: 'EUR', to: 'USD').pluck(:value)
# => [1.162, 1.162, 1.161, 1.161, 1.163, …]
Add these lines to your application's Gemfile
:
# Store and retrieve the currency from the database.
gem 'active_currency'
And in config/initializers/money.rb
:
MoneyRails.configure do |config|
config.default_bank = ActiveCurrency::Bank.new
end
Then call bin/rake db:migrate
to create the table that holds
the currency rates and fill it for the first time.
By defaut it uses the eu_central_bank to update the currency rates.
If you prefer another API, you can provide any Money-compatible bank when
calling ActiveCurrency::AddRates
. For example with the
money-open-exchange-rates gem:
require 'money/bank/open_exchange_rates_bank'
bank = Money::Bank::OpenExchangeRatesBank.new(Money::RatesStore::Memory.new)
bank.app_id = '…'
ActiveCurrency::AddRates.call(%w[EUR USD], bank: bank)
The first currency you give to AddRates
is considered the default currency
against which other currency rates will be guessed if they are unavailable.
In your app test suite you may not want to have to fill your database to be able to exchange currencies.
For that, you can use a fake rate store in your rails_helper.rb
:
MoneyRails.configure do |config|
rate_store = Money::RatesStore::Memory.new.tap do |store|
store.add_rate('USD', 'EUR', 1.5)
store.add_rate('EUR', 'USD', 1.4)
end
config.default_bank = Money::Bank::VariableExchange.new(rate_store)
end
Please file issues and pull requests on GitHub.
Install:
BUNDLE_GEMFILE=Gemfile-rails6.0 bundle install
Launch specs and linters:
BUNDLE_GEMFILE=Gemfile-rails6.0 bin/rake
Update CHANGELOG.md
, update version in lib/active_currency/version.rb
.
Then:
gem install bundler:1.17.2
BUNDLE_GEMFILE=Gemfile-rails4.2 bundle update
BUNDLE_GEMFILE=Gemfile-rails5.2 bundle update
gem install bundler:2.1.2
BUNDLE_GEMFILE=Gemfile-rails6.0 bundle update
git add CHANGELOG.md lib/active_currency/version.rb Gemfile-rails*.lock
git commit -m v`ruby -r./lib/active_currency/version <<< 'puts ActiveCurrency::VERSION'`
bin/rake release
The gem is available as open source under the terms of the MIT License.