To add money-rails to your Rails application, add the gem to your Gemfile using Bundler or install it directly via the gem command.

For non-Rails rack-based applications, you must manually initialize the library during your application's boot process by calling MoneyRails::Hooks.init.

bundle add money-rails

Or

$ gem install money-rails

For rack-based applications without Rails

MoneyRails::Hooks.init

Money-Rails provides reversible migration helpers to add monetized columns to your database. You can use add_monetize to add a money field or remove_monetize if writing separate up and down methods. These helpers can be customized in a MoneyRails.configure block.

When using add_monetize, you can specify options for the currency column, such as currency: { present: false } if you do not want a separate currency column.

class MonetizeProduct < ActiveRecord::Migration
  def change
    add_monetize :products, :price

    # OR

    change_table :products do |t|
      t.monetize :price
    end
  end
end

# Example without a currency column
class MonetizeItem < ActiveRecord::Migration
  def change
    add_monetize :items, :price, currency: { present: false }
  end
end

Money-Rails provides test helpers to verify that attributes are correctly monetized.

RSpec: Require money-rails/test_helpers in your spec_helper.rb. Minitest: Require money-rails/test_helpers and include MoneyRails::TestHelpers in your test class.

You can use the monetize matcher to check for column mapping, nil allowance, custom names, specific currencies, or model-based currency columns.

You can generate a configuration initializer to define the default currency and other global settings for your Rails application using the Rails generator:

bin/rails generate money_rails:initializer

This creates a file where you can manage configuration parameters such as the default currency value.

$ bin/rails generate money_rails:initializer

When using Money-Rails with Mongoid, Money objects are converted into a database-friendly hash format. This allows Mongoid to store the monetary value and its currency within a single document field.

An instance of Money is converted to a hash containing:

• cents: The amount converted to a float.
• currency_iso: The ISO currency code.

Example of the stored structure:

{
  "cents": 100.0,
  "currency_iso": "USD"
}

The money-rails gem provides a custom field type for RailsAdmin that allows money fields to be handled as Decimal types while supporting humanized formatting. Once the gem is installed, the Money field type is automatically registered with RailsAdmin.

You can use the :pretty_value instance option in your RailsAdmin configuration to display money values using humanized formatting (including the currency symbol) instead of the raw decimal value.

To configure MoneyRails settings, use the MoneyRails.configure block within a Rails initializer. This allows you to set global defaults for currencies, rounding modes, and database column configurations.

MoneyRails.configure do |config|
  config.default_currency = :eur
end

Money-Rails provides several helpers to format money objects for display in views:

Note: humanized_money and humanized_money_with_symbol will hide cents if they are zero, unless config.no_cents_if_whole is set to false in your configuration.

In Mongoid, you can use Money directly as a field type in your document definitions. This allows the field to store both the cents and the currency information.

class Product
  include Mongoid::Document

  field :price, type: Money
end

obj = Product.new
obj.price = Money.new(100, 'EUR')
obj.save

# Accessing the underlying hash
obj[:price] # => {cents: 100, currency_iso: "EUR"}