如何实现单例模型 [英] How to implement a singleton model

问题描述

我在 rails 中有一个站点，并且想要进行站点范围的设置.如果发生特定事件，我的应用程序的一部分可以通过短信通知管理员.这是我希望通过站点范围的设置进行配置的功能示例.

I have a site in rails and want to have site-wide settings. One part of my app can notify the admin by SMS if a specific event happens. This is an example of a feature that I want configurable via the site-wide settings.

所以我想我应该有一个设置模型或其他东西.它需要是一个模型，因为我希望能够 has_many :contacts 用于 SMS 通知.

So I was thinking I should have a Setting model or something. It needs to be a model because I want to be able to has_many :contacts for the SMS notification.

问题是设置模型的数据库中只能有一个帖子.所以我在考虑使用单例模型，但这只会阻止创建新对象，对吗?

The problem is that there can only be one post in the database for the settings model. So I was thinking of using a Singleton model but that only prevents new object to be created right?

我是否仍然需要像这样为每个属性创建 getter 和 setter 方法:

Would I still need to create getter and setter methods for each attribute like so:

def self.attribute=(param)
  Model.first.attribute = param
end

def self.attribute
  Model.first.attribute
end

直接使用 Model.attribute 但总是创建它的一个实例并使用它可能不是最佳实践吗?

Is it perhaps not best-practice to use Model.attribute directly but always create an instance of it and use that?

我应该在这里做什么?

推荐答案

我不确定我是否会为了这种基本需求而浪费数据库/ActiveRecord/Model 开销.这些数据是相对静态的(我假设)并且不需要即时计算(包括数据库查找).

I am not sure I'd waste the database/ActiveRecord/Model overhead for such a basic need. This data is relatively static (I am assuming) and on the fly calculations aren't necessary (including database lookups).

话虽如此，我建议您使用站点范围的设置定义一个 YAML 文件，并定义一个将设置加载到常量中的初始化文件.您几乎不会有那么多不必要的活动部件.

Having said that, I'd recommend you define a YAML file with your site-wide settings and define an initializer file that loads the settings into a constant. You won't have nearly as many of the unnecessary moving parts.

数据没有理由不能只是放在内存中并为您节省大量的复杂性.常量随处可用，它们不需要初始化或实例化.如果将类用作单例绝对至关重要，我建议您做以下两件事:

There is no reason that data couldn't just sit in memory and save you a ton of complexity. Constants are available everywhere, and they don't need to be initialized or instantiated. If its absolutely critical that you utilize a class as a singleton, I'd recommend doing these two things:

1. 取消定义初始化/新方法
2. 只定义 self.* 方法，这样你就不可能维护状态

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