rails5-depot/db/migrate/20161116183040_fill_price_in_line_items.rb

class FillPriceInLineItems < ActiveRecord::Migration[5.0]
  def up
    LineItem.all.each do |item|
      product = Product.find(item.product_id)
      item.price = product.price
      item.save!
    end
  end

  def down
  end
end