Economy

High performance multicurrency money for rails.

Why

I did this gem to:

• Keep rates cached in redis for optimal performance and sync between instances.
• Have an out of the box working rates service.
• Be able to make sql queries without the need to convert integers into decimals.
• Share a common currency column for multiple money fields if a need it.
• Avoid the need to manually format the string representation in views.

Install

Put this line in your Gemfile:

gem 'economy'

Then bundle:

$ bundle

To install Redis you can use homebrew:

$ brew install redis

Configuration

Generate the configuration file:

$ bundle exec rails g economy:install

Set the global settings:

Economy.configure do |config|

  config.redis = Redis.new(url: 'redis://localhost:6379/0')
  config.rates = :yahoo
  config.default_currency = 'USD'

  config.add_currency(
    iso_code: 'USD',
    iso_number: 840,
    symbol: 'U$S',
    decimals: 2
  )
  config.add_currency(
    iso_code: 'UYU',
    iso_number: 858,
    symbol: '$U',
    decimals: 2
  )

end

Usage

Definitions

Add the money columns to your tables:

class AddPriceToProducts < ActiveRecord::Migration
  def change
    add_column :products, :price, :decimal, precision: 24, scale: 6
    add_column :products, :currency, :string, limit: 3 # Or :price_currency
  end
end

Define the money field in your models:

class Product < ActiveRecord::Base
  monetize :price
end

Attributes

If you want to assign values, everything continuos working the same:

product.price = 20.00
product.currency = 'USD'

Arithmetics are intuitive:

product.price * 2 # => U$S 40
product.price / 2 # => U$S 10

product.price + Economy::Money.new(10, 'USD') # => U$S 30
product.price - Economy::Money.new(10, 'USD') # => U$S 10

To exchange to another currency:

product.price.exchange_to 'UYU'

The formatting method is to_s, it uses active support, so there is no need to call a helper in your views:

<%= product.price %>

Rates

You can use rake task:

$ bundle exec rake economy:update_rates

Or the plain method:

Economy.update_rates

NOTE: You probably want to put the rake task into a cronjob.

Credits

This gem is maintained and funded by mmontossi.

License

It is free software, and may be redistributed under the terms specified in the MIT-LICENSE file.