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Integration of RubyMoney - Money with Rails

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RubyMoney - Money-Rails endorse

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This library provides integration of money gem with Rails.

Use 'monetize' to specify which fields you want to be backed by Money objects and helpers provided by the money gem.

Currently, this library is in active development mode, so if you would like to have a new feature feel free to open a new issue here. You are also welcome to contribute to the project.


Add this line to your application's Gemfile:

gem 'money-rails'

And then execute:

$ bundle

Or install it yourself as:

$ gem install money-rails

You may also install money configuration initializer:

$ rails g money_rails:initializer

There, you can define the default currency value and set other configuration parameters for the rails app.



Usage example

For example, we create a Product model which has an integer price_cents column and we want to handle it by using a Money object instead:

class Product < ActiveRecord::Base

  monetize :price_cents


Now each Product object will also have an attribute called price which is a Money object and can be used for money comparisons, conversions etc.

In this case the name of the money attribute is created automagically by removing the _cents suffix of the column name.

If you are using another db column name or you prefer another name for the money attribute, then you can provide as argument with a string value to the monetize macro:

monetize :discount_subunit, :as => "discount"

Now the model objects will have a discount attribute which is a Money object, wrapping the value of discount_subunit column to a Money instance.

Migration helpers

If you want to add money field to product model you may use add_money helper. That helper might be customized inside MoneyRails.configure block. You should customize add_money helper to match the most common use case and utilize it across all migrations.

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

    # OR

    change_table :products do |t| :price

Another example where the currency column is not including:

class MonetizeItem < ActiveRecord::Migration
  def change
    add_money :items, :price, currency: { present: false }

add_money helper is revertable, so you may use it inside change migrations. If you writing separate up and down methods, you may use remove_money helper.

Allow nil values

If you want to allow the assignment of nil and/or blank values to a specific monetized field, you can use the :allow_nil parameter like this:

# in Product model
monetize :optional_price_cents, :allow_nil => true

# in Migration
def change
  add_money :products, :optional_price, amount: { null: true, default: nil }

# then blank assignments are permitted
product.optional_price = nil # returns without errors
product.optional_price # => nil
product.optional_price_cents # => nil

Numericality validation options

You can also pass along numericality validation options such as this:

monetize :price_in_a_range_cents, :allow_nil => true,
  :numericality => {
    :greater_than_or_equal_to => 0,
    :less_than_or_equal_to => 10000

Or, if you prefer, you can skip validations entirely for the attribute. This is useful if chosen attributes are aggregate methods and you wish to avoid executing them on every record save.

monetize :price_in_a_range_cents, :disable_validation => true

Mongoid 2.x and 3.x

Money is available as a field type to supply during a field definition:

class Product
  include Mongoid::Document

  field :price, type: Money

obj =
# => #<Product _id: 4fe865699671383656000001, _type: nil, price: nil>

# => nil

obj.price =, 'EUR')
# => #<Money cents:100 currency:EUR>

#=> #<Money cents:100 currency:EUR>
# => true

# => #<Product _id: 4fe865699671383656000001, _type: nil, price: {:cents=>100, :currency_iso=>"EUR"}>

#=> #<Money cents:100 currency:EUR>

## You can access the money hash too :
# => {:cents=>100, :currency_iso=>"EUR"}

The usual options on field as index, default, ..., are available.

Method conversion

Method return values can be converted in the same way attributes are converted. For example:

class Transaction < ActiveRecord::Base

  monetize :price_cents
  monetize :tax_cents
  monetize :total_cents
  def total_cents
    return price_cents + tax_cents


Now each Transaction object has a method called total which returns a Money object.


Money-rails supports a set of options to handle currencies for your monetized fields. The default option for every conversion is to use the global default currency of Money library, as given in the configuration initializer of money-rails:

# config/initializers/money.rb
MoneyRails.configure do |config|

  # set the default currency
  config.default_currency = :usd


In many cases this is not enough, so there are some other options to satisfy your needs.

Model Currency

You can define a specific currency for an activerecord model (not for mongoid). This currency is used for the creation and conversions of the Money objects referring to every monetized attributes of the specific model. This means it overrides the global default currency of Money library. To attach a currency to a model use the register_currency macro:

# app/models/product.rb
class Product < ActiveRecord::Base

  # Use EUR as model level currency
  register_currency :eur

  monetize :discount_subunit, :as => "discount"
  monetize :bonus_cents


Now and product.bonus will return a Money object using EUR as currency, instead of the default USD.

Attribute Currency (:with_currency)

By using the key :with_currency with a currency symbol value in the monetize macro call, you can define a currency in a more granular way. This way you attach a currency only to the specific monetized model attribute. It also allows to override both the model level and the global default currency:

# app/models/product.rb
class Product < ActiveRecord::Base

  # Use EUR as model level currency
  register_currency :eur

  monetize :discount_subunit, :as => "discount"
  monetize :bonus_cents, :with_currency => :gbp


In this case the product.bonus will return a Money object of GBP currency, whereas # => EUR

Instance Currencies

All the previous options do not require any extra model field to hold currency values. If you need to provide differrent currency per model instance, then you need to add a column with the name currency in your db table. You should specify with_model_currency as an argument to the monetize macro. Money-rails will use this knowledge to override the model level and global default values. Non-nil instance currency values also override attribute currency values, so they have the highest precedence.

class Transaction < ActiveRecord::Base

  # This model has a separate currency column
  attr_accessible :amount_cents, :currency, :tax_cents

  # Use model level currency
  register_currency :gbp

  monetize :amount_cents, with_model_currency: :amount_currency
  monetize :tax_cents, with_model_currency: :tax_currency


# Now instantiating with a specific currency overrides
# the model and global currencies
t = => 2500, :currency => "CAD")
t.amount ==, "CAD") # true

Configuration parameters

You can handle a bunch of configuration params through money.rb initializer:

MoneyRails.configure do |config|

  # To set the default currency
  config.default_currency = :usd

  # Add custom exchange rates
  config.add_rate "USD", "CAD", 1.24515
  config.add_rate "CAD", "USD", 0.803115

  # To handle the inclusion of validations for monetized fields
  # The default value is true
  config.include_validations = true

  # Default ActiveRecord migration configuration values for columns:
  # config.amount_column = { prefix: '',           # column name prefix
  #                          postfix: '_cents',    # column name  postfix
  #                          column_name: nil,     # full column name (overrides prefix, postfix and accessor name)
  #                          type: :integer,       # column type
  #                          present: true,        # column will be created
  #                          null: false,          # other options will be treated as column options
  #                          default: 0
  #                        }
  # config.currency_column = { prefix: '',
  #                            postfix: '_currency',
  #                            column_name: nil,
  #                            type: :string,
  #                            present: true,
  #                            null: false,
  #                            default: 'USD'
  #                          }

  # Register a custom currency
  # config.register_currency = {
  #   :priority            => 1,
  #   :iso_code            => "EU4",
  #   :name                => "Euro with subunit of 4 digits",
  #   :symbol              => "€",
  #   :symbol_first        => true,
  #   :subunit             => "Subcent",
  #   :subunit_to_unit     => 10000,
  #   :thousands_separator => ".",
  #   :decimal_mark        => ","
  # }

  # Specify a rounding mode
  # Any one of:
  # BigDecimal::ROUND_UP,
  # BigDecimal::ROUND_DOWN,
  # BigDecimal::ROUND_HALF_UP,
  # BigDecimal::ROUND_HALF_DOWN,
  # BigDecimal::ROUND_HALF_EVEN,
  # BigDecimal::ROUND_CEILING,
  # BigDecimal::ROUND_FLOOR
  # set to BigDecimal::ROUND_HALF_EVEN by default
  config.rounding_mode = BigDecimal::ROUND_HALF_UP 

  # Set money formatted output globally.
  # Default value is nil meaning "ignore this option".
  # Options are nil, true, false.
  # config.no_cents_if_whole = nil
  # config.symbol = nil
  # config.sign_before_symbol = nil
  • default_currency: Set the default (application wide) currency (USD is the default)
  • include_validations: Permit the inclusion of a validates_numericality_of validation for each monetized field (the default is true)
  • register_currency: Register one custom currency. This option can be used more than once to set more custom currencies. The value should be a hash of all the necessary key/value pairs (important keys: :priority, :iso_code, :name, :symbol, :symbol_first, :subunit, :subunit_to_unit, :thousands_separator, :decimal_mark).
  • add_rate: Provide custom exchange rate for currencies in one direction only! This rate is added to the attached bank object.
  • default_bank: The default bank object holding exchange rates etc. (
  • no_cents_if_whole: Force Money#format method to use its value as the default for no_cents_if_whole key.
  • symbol: Use its value as the default for symbol key in Money#format method.
  • sign_before_symbol: Force Money#format to place the negative sign before the currency symbol.
  • amount_column: Provide values for the amount column (holding the fractional part of a money object).
  • currency_column: Provide default values or even disable (present: false) the currency column.
  • rounding_mode: Set Money.rounding_mode to one of the BigDecimal constants


  • the currency_symbol helper method
<%= currency_symbol %>

This will render a span dom element with the default currency symbol.

  • the humanized_money helper method
<%= humanized_money @money_object %>

This will render a formatted money value without the currency symbol and without the cents part if it contains only zeros (uses :no_cents_if_whole flag).

  • humanize with symbol helper
<%= humanized_money_with_symbol @money_object %>

This will render a formatted money value including the currency symbol and without the cents part if it contains only zeros.

  • get the money value without the cents part
<%= money_without_cents @money_object %>

This will render a formatted money value without the currency symbol and without the cents part.

  • get the money value without the cents part and including the currency symbol
<%= money_without_cents_and_with_symbol @money_object %>

This will render a formatted money value including the currency symbol and without the cents part.


If you use Rspec there is an test helper implementation. Just write require "money-rails/test_helpers" in spec_helper.rb and include MoneyRails::TestHelpers inside a describe block you want to use the helper.

  • the monetize matcher
monetize(:price_cents).should be_true

This will ensure that a column called price_cents is being monetized.

monetize(:price_cents).as(:discount_value).should be_true

By using as chain you can specify the exact name to which a monetized column is being mapped.

monetize(:price_cents).with_currency(:gbp).should be_true

By using the with_currency chain you can specify the expected currency for the chosen money attribute. (You can also combine all the chains.)

For examples on using the test_helpers look at test_helpers_spec.rb

Supported ORMs/ODMs

  • ActiveRecord (>= 3.x)
  • Mongoid (2.x, 3.x)

Supported Ruby interpreters

  • MRI Ruby >= 1.9.2

You can see a full list of the currently supported interpreters in travis.yml



  1. Fork the repo
  2. Run the tests
  3. Make your changes
  4. Test your changes
  5. Create a Pull Request

How to run the tests

Our tests are executed with several ORMs - see Rakefile for details. To install all required gems run rake spec:all That command will take care of installing all required gems for all the different Gemfiles and then running the test suite with the installed bundle.

You can also run the test suite against a specific ORM or Rails version, rake -T will give you an idea of the possible task (take a look at the tasks under the spec: namespace).

If you are testing against mongoid, make sure to have the mongod process running before executing the suite, (E.g. sudo mongod --quiet)



MIT License. Copyright 2012-2014 RubyMoney.

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