Rails: money gem converts all amounts to zero

Question

I\'m trying to use the money gem to handle currency in my app but I\'m running into a strange error. This is what I have in my \"record\" model:

composed_of          


        

Answer 1

EDIT: Added Bonus at the end of the answer

Well, your question was interesting to me so I decided to try myself.

This works properly:

1) Product migration:

create_table :products do |t|
  t.string :name
  t.integer :cents, :default => 0
  t.string :currency
  t.timestamps
end

2) Product model

class Product < ActiveRecord::Base

   attr_accessible :name, :cents, :currency

  composed_of :price,
    :class_name => "Money",
    :mapping => [%w(cents cents), %w(currency currency_as_string)],
    :constructor => Proc.new { |cents, currency| Money.new(cents || 0, currency || Money.default_currency) },
    :converter => Proc.new { |value| value.respond_to?(:to_money) ? value.to_money : raise(ArgumentError, "Can't convert #{value.class} to Money") }
end

3) Form:

<%= form_for(@product) do |f| %>
  

    <%= f.label :name %>

    <%= f.text_field :name %> 
  
  

    <%= f.label :cents %>

    <%= f.text_field :cents %>
  
  

    <%= f.label :currency %>
      
   <%= f.select(:currency,all_currencies(Money::Currency::TABLE), {:include_blank => 'Select a Currency'}) %>
  
  

    <%= f.submit %>
  
<% end %>

4) Products Helper (handmade):

module ProductsHelper
  def major_currencies(hash)
    hash.inject([]) do |array, (id, attributes)|
      priority = attributes[:priority]
      if priority && priority < 10
        array ||= []
        array << [attributes[:name], attributes[:iso_code]]
      end
      array
    end
  end

  def all_currencies(hash)
    hash.inject([]) do |array, (id, attributes)|
      array ||= []
      array << [attributes[:name], attributes[:iso_code]]
      array
    end
  end
end

BONUS:

If you want to add currency exchange rates:

1) Your gemfile

gem 'json' #important, was not set as a dependency, so I add it manually
gem 'google_currency'

2) Initializer

create money.rb in you initializers folder and put this inside:

require 'money'
require 'money/bank/google_currency'
Money.default_bank = Money::Bank::GoogleCurrency.new

reboot your server

3) Play!

Wherever you are, you can exchange the money.

Product.first.price.exchange_to('USD')

Display with nice rendering:

Product.first.price.format(:symbol => true)