Handling with money in Mongoid

gistfile1.txt

class Product
  include Mongoid::Document

  field :price,    type: Money
end

Money.class_eval do

  # Converts an object of this instance into a database friendly value.
  def mongoize
    [cents, currency.to_s]
  end

  class << self

    # Get the object as it was stored in the database, and instantiate
    # this custom class from it.
    def demongoize(object)
      cur = object[1] || Money.default_currency
      Money.new(object[0], cur)
    end

    # Takes any possible object and converts it to how it would be
    # stored in the database.
    def mongoize(object)
      case object
      when Money
        object.mongoize
      else object
      end
    end

    # Converts the object that was supplied to a criteria and converts it
    # into a database friendly form.
    def evolve(object)
      case object
      when Money then object.mongoize
      else object
      end
    end
  end

end

product = Product.new(:price => Money.new(1000, 'EUR'))
product.price.format
# => "€10.00"