Add lock_version to Spree::StockItem

db/migrate/20200512070717_add_lock_version_to_stock_items.rb

@@ -0,0 +1,5 @@
+class AddLockVersionToStockItems < ActiveRecord::Migration
+  def change
+    add_column :spree_stock_items, :lock_version, :integer, default: 0
+  end
+end

db/schema.rb

@@ -899,6 +899,7 @@ ActiveRecord::Schema.define(version: 20200623140437) do
     t.datetime "updated_at"
     t.boolean  "backorderable",     default: false
     t.datetime "deleted_at"
+    t.integer  "lock_version",      default: 0
   end
 
   add_index "spree_stock_items", ["stock_location_id", "variant_id"], name: "stock_item_by_loc_and_var_id", using: :btree