Migrations and Models for Tripartite Identity in Rails 5.2

account.rb

# frozen_string_literal: true

class Account < UUIDRecord
  # This project uses a tripartite identity pattern
  # (see http://habitatchronicles.com/2008/10/the-tripartite-identity-pattern/)
  # This class is the ACCOUNT component.
  # The other components are User and Profile.

  # Initializers
  after_initialize :add_profile, if: :new_record?

  has_many :users, dependent: :destroy
  has_many :profiles, dependent: :destroy

  # TODO: this should be improved to actually be user controlled
  def primary_user
    users.first
  end

  private

  def add_profile
    profiles.build
  end
end

Gemfile

gem 'devise'
gem 'devise-security'

profile.rb

# frozen_string_literal: true

class Profile < UUIDRecord
  # This project uses a tripartite identity pattern
  # (see http://habitatchronicles.com/2008/10/the-tripartite-identity-pattern/)
  # This class is the PUBLIC component.
  # The other components are Account and User.

  belongs_to :account
  after_initialize :ensure_account

  def full_name
    "#{first_name} #{last_name}"
  end

  private

  def ensure_account
    build_account if account.blank?
  end
end

tripartite_migration.rb

class CreateTripartiteModels < ActiveRecord::Migration[5.2]
  def change
    create_table :accounts, id: false do |t|
      t.string :id, limit: 36, primary_key: true, null: false
      t.timestamps
    end

    create_table :users, id: false do |t|
      t.string :id, limit: 36, primary_key: true, null: false
      t.references :account, type: :string, index: true, foreign_key: true

      ## Database authenticatable
      t.string :email,              null: false, default: ''
      t.string :encrypted_password, null: false, default: ''

      ## Recoverable
      t.string   :reset_password_token
      t.datetime :reset_password_sent_at

      ## Rememberable
      t.datetime :remember_created_at

      ## Trackable
      t.integer  :sign_in_count, default: 0, null: false
      t.datetime :current_sign_in_at
      t.datetime :last_sign_in_at
      t.string   :current_sign_in_ip
      t.string   :last_sign_in_ip

      ## Confirmable
      t.string   :confirmation_token
      t.datetime :confirmed_at
      t.datetime :confirmation_sent_at
      t.string   :unconfirmed_email # Only if using reconfirmable

      ## Lockable
      t.integer  :failed_attempts, default: 0, null: false # Only if lock strategy is :failed_attempts
      t.string   :unlock_token # Only if unlock strategy is :email or :both
      t.datetime :locked_at

      ## Password Expirable
      t.datetime :password_changed_at

      t.timestamps null: false
    end

    create_table :profiles, id: false do |t|
      t.string :id, limit: 36, primary_key: true, null: false
      t.references :account, type: :string, index: true, foreign_key: true

      t.string :first_name
      t.string :last_name

      t.timestamps
    end

    ## Password Archivable (devise-security)
    create_table :old_passwords do |t|
      t.string :encrypted_password, null: false
      t.string :password_archivable_type, null: false
      t.string :password_archivable_id, null: false
      t.string :password_salt
      t.datetime :created_at
    end

    add_index :users, :email,                unique: true
    add_index :users, :reset_password_token, unique: true
    add_index :users, :confirmation_token,   unique: true
    add_index :users, :unlock_token,         unique: true

    add_index :users, :password_changed_at
    add_index :old_passwords, [:password_archivable_type, :password_archivable_id], name: :index_password_archivable
  end
end

user.rb

# frozen_string_literal: true

class User < UUIDRecord
  # This project uses a tripartite identity pattern
  # (see http://habitatchronicles.com/2008/10/the-tripartite-identity-pattern/)
  # This class is the LOGIN component.
  # The other components are Account and Profile.

  # devise :database_authenticatable, :registerable, :confirmable, :lockable,
  #        :recoverable, :rememberable, :trackable, :timeoutable,
  #        :validatable, :password_archivable

  belongs_to :account
  has_many :profiles, through: :account

  after_initialize :ensure_account, if: :new_record?

  private

  def ensure_account
    build_account
  end
end

uuid_record.rb

# frozen_string_literal: true

# :nocov:
class UUIDRecord < ApplicationRecord
  self.abstract_class = true

  after_initialize :set_uuid

  def set_uuid
    self.id = SecureRandom.uuid if id.blank?
  end
end
# :nocov: