Adds an add_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 “has_extra_data”

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_account.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