DB history for checkouts (and other stuff)

20130128152044_create_user_history.rb

class CreateUserHistory < ActiveRecord::Migration
  def change
    create_table :user_history do |t|
      t.association :user # Most things we care about should have a user, but nil-able if not
      t.string :username # stamped from user.username
      t.string :message # Log-like message
      t.string :code # Specific token for sorting, or tracking error or status
      t.float :timing # Optional for keeping timing like response time

      #NOTE:  has_many :history_snapshots # snapshot data about relevant objects
      t.datetime :created_at

    end
  end
end

h = UserHistory.create(user: current_user, message: 'starting checkout'() # Direct create on class
h.snapshots << @cart

current_user.history(user: current_user, message: 'starting checkout', snapshots: [@cart]) # Method on User

@cart.history('starting checkout') # Or method on Order

class CreateHistorySnapshots < ActiveRecord::Migration
  def change
    create_table :history_snapshots do |t|
      t.references :subject, :polymorphic => true # subject record id and type (i.e Order)
      t.string :snapshot

      t.datetime :created_at
    end
  end
end

Also considering taking this a step further and encapsulating all logging (at least in checkouts), ala Freeman: http://www.mockobjects.com/2007/04/test-smell-logging-is-also-feature.html