class CreateStockEvents < ActiveRecord::Migration[4.2] class StockEvent < ActiveRecord::Base; end class StockTaking < ActiveRecord::Base; end def change rename_table :deliveries, :stock_events rename_column :stock_changes, :delivery_id, :stock_event_id add_column :stock_events, :type, :string, default: 'Delivery', null: false reversible do |dir| dir.up do change_column_default :stock_events, :type, nil diff = [StockEvent.maximum(:id) + 1 - StockTaking.minimum(:id), 0].max execute "UPDATE stock_changes SET stock_event_id = stock_taking_id + #{diff} WHERE stock_taking_id IS NOT NULL" execute "INSERT INTO stock_events (type, id, date, note, created_at) SELECT 'StockTaking', id + #{diff}, date, note, created_at FROM stock_takings" remove_column :stock_changes, :stock_taking_id drop_table :stock_takings end dir.down do create_table :stock_takings do |t| t.date :date t.text :note t.datetime :created_at end add_column :stock_changes, :stock_taking_id, :integer execute "INSERT INTO stock_takings (id, date, note, created_at) SELECT id, date, note, created_at FROM stock_events WHERE type = 'StockTaking'" execute "DELETE FROM stock_events WHERE type = 'StockTaking'" execute "UPDATE stock_changes SET stock_taking_id = stock_event_id, stock_event_id = NULL WHERE stock_event_id IN (SELECT id FROM stock_takings)" end end end end