ruby-on-rails - 如何在 Rails 中创建时使用附加到字符串的 id 更新字段

Question

我有下表和相应的模型：

Orders
ID|ORDER_REF|....

订单参考的格式为'ORDER#000-00'+ORDER.ID 问题是我需要启用它，以便在插入时设置订单参考。有没有办法做到这一点而无需在插入后进行更新，我在这里使用 RoR。

Answer 1

Do you really need that data in your database? The best way would be to just have a method on your model that returns the order ref in the desired format, based on the id in the database.

class Order < ActiveRecord::Base
  def order_ref
    "ORDER#000-#{self.id.to_s.rjust(3, '0')}"
  end
end

With the abobe you can do this:

order = Order.create(params[:order])
order.id #=> 12
order.order_ref #=> "ORDER#000-012"

If you do need the order ref in the database, I recommend using an after_create callback:

class Order < ActiveRecord::Base
  after_create :generate_order_ref

  def generate_order_ref
    self.order_ref = "ORDER#000-#{self.id.to_s.rjust(3, '0')}"
    save
  end
end

This does do an update after inserting, but I don't see any problem with that.