Accounting sucks. Well if you are trying to do it right it does. Bean machine gives you the power of an immutable double entry accounting system through the use of a simple transfer method. The idea is to make accounting easy by breaking it into easy to follow steps. Transfer this much from this account to that account.

Bean Machine is very rough right now. The basics work but you will need to do some manual work setting up the db and such. It will change and it will break. But that just means it is an active project and will make rapid progress. Until it gets a couple good point releases you probably shouldn't use it in production. I probably will be using it in production to help figure out the best way to take it but you shouldn't. Just don't.

Bean Machine is hosted on GemCutter ... I mean RubyGems, So just install like a normal gem.

sudo gem install bean_machine --pre

Until nice generators are done you can manually make a migration with the following structure. It will change frequently while the kinks are getting worked out.

create_table :bean_transfers, :force => true do |t|
  t.references :user
  t.references :accountable, :polymorphic => true

  t.string :state
  t.integer :amount
  t.string :debit
  t.string :credit
  t.string :currency, :null => false, :default => 'USD'
  t.string :event, :null => false, :default => 'transfer'
  t.boolean :success
  t.string :reference
  t.string :message
  t.text :params
  t.boolean :test
  t.boolean :affect_balance
end

Bean Machine is based on the double entry accounting system. Every transfer is moving money from one account to another account. Eventually I will give a nice tutorial on basic accounting principles but it will have to wait.

An example is worth a thousand words so lets do a quick one.

class User < ActiveRecord::Base
  # tell it who has the balances
  include Bean::User
  
  has_many :invoices
end
  
class Invoice < ActiveRecord::Base
  # this adds the transfer method
  include Bean::Machine
  
  belongs_to :user
  
  # just transfer an amount from a credit account to a debit account.
  # it doesn't really matter what account you credit and what you
  # debit as long as you keep it consistant.
  def pay(amount)
    transfer amount.to_money, :credit => :payments, :debit => :invoice
  end
end

# just make a user
@user = User.create

# give them a couple invoices
@invoice = @user.invoices.create

# pay some amount on the invoice
@invoice.pay(10)

# lookup the balance for a given account
@user.balance(:invoice) #=> Money object with value of 1000 cents
@user.balance(:invoice).to_s #=> '10.00'

# pay more on the invoice
@invoice.pay(20)

# and the balance increases
@user.balance(:invoice).to_s #=> '30.00' 
@user.balance(:payments).to_s #=> '30.00' 

This example has not been tested yet but is here to give you a basic idea of how it works.

• Lots and lots
• Mixins for common accounting transactions (payment, invoice, etc)
• Integrate ActiveMerchant
• Pluggable transfer store (noSQL)
• ORM independent

• Fork the project.
• Make your feature addition or bug fix.
• Add tests for it. This is important so I don't break it in a future version unintentionally.
• Commit, do not mess with rakefile, version, or history. (if you want to have your own version, that is fine but bump version in a commit by itself I can ignore when I pull)
• Send me a pull request. Bonus points for topic branches.

Copyright (c) 2010 Josh Robinson . See LICENSE for details.