Adds an has_extra_data method to ActiveRecord that invisibly includes an extra data table. Use with STI to keep your database clean. It removes the need to have lots of nullable columns.

Usage

Use in Rails 3 app. Add to bundler: gem 'super_sti', :git => "git://github.com/ihid/super_sti.git"

Tests

Uses rspec for testing. Run tests with rspec spec/*

Todo

• Automatically load extra data class with main class.
• Automatically load associations in main class.
• Automatically pass attributes through to main class.

Example

Usage:

Account.each do |account|
  puts account.balance
end

BankAccount.each do |bank_account|
  puts bank_account.balance
  puts bank_account.bank.name
end

Classes:

class Account < ActiveRecord::Base
  before_create :set_initial_balance

private
  def set_initial_balance
    self.balance = 0
    true
  end
end

class BankAccount < Account
  has_extra_data do
    belongs_to :bank
  end
end

class CreditCard < Account
  has_extra_data
end

class Bank < ActiveRecord::Base
  has_one :bank_account
end

Database Schema:

create_table :accounts do |t|
  t.float :balance
end

create_table :bank_account_data do |t|
  t.integer :bank_account_id, :null => false
  t.integer :bank_id, :null => false
  t.string :account_number, :null => false
  t.string :sort_code, :null => false
end

create_table :credit_card_data do |t|
  t.integer :credit_card_id, :null => false
  t.string :credit_card_number, :null => false
  t.date :expiry_date, :null => false
end

create_table :banks do |t|
  t.string :name, :null => false
end