Example.rb

require 'rubygems'
require 'dm-core'

db_url = "sqlite3://#{File.dirname(__FILE__)}/example.db"
DataMapper.setup(:default, db_url)

class LedgerEntry
  include DataMapper::Resource

  property    :id, Serial
  property    :description,  String
  property    :amount,       Float
end

class Ledger
  include DataMapper::Resource
	include ALC::DbObject

  property    :id, Serial
  property    :total, Float, :required => true, :default => 0
  has n,      :entries, :model => 'LedgerEntry'

	before :destroy do
		entries.destroy if entries
	end
end

class Option
  include DataMapper::Resource
	include ALC::DbObject

  property  :id, Serial
  property  :title, String
  property  :duration, Float  # years until money runs out
  has 1,    :initial_costs, :model => 'Ledger'
  has 1,    :recurring_costs, :model => 'Ledger'

	before :destroy do
		initial_costs.destroy if initial_costs
		recurring_costs.destroy if recurring_costs
	end
end

class Account
  include DataMapper::Resource
	include ALC::DbObject

  property    :id, Serial
  has 1,      :assets, :model => 'Ledger'
  has 1,      :income, :model => 'Ledger'
  has 1,      :expenses, :model => 'Ledger'
  has n,      :options, :model => 'Option'

	# Should never delete an account!
	before :destroy do
		throw halt
	end
end

# instructs DataMapper to setup your database as needed
#DataMapper.auto_upgrade!
DataMapper.auto_migrate!

example_spec.rb

require 'rubygems'
require 'spec'
require 'Model'

describe "ALC::Model::" do

	it "Account.new should be able to create new account" do
		account = Account.new
		account.save.should be_true
	end

	it "Option.new should be able to create new option with account" do
		account = Account.new
		account.save.should be_true
		option = Option.new ({ :title => "New Option", :account_id => account.id, })
		option.save.should be_true
	end

	it "Option.new should be able to create new ledger with Option " do
		account = Account.new
		account.save.should be_true

		option = Option.new ({ :title => "New Option", :account_id => account.id})
		option.save.should be_true

		ledger = Ledger.new( { :total => "3.3", :option_id => option.id})
		ledger.save.should be_true
	end
end