Rails 模型上的动态方法

发布于 2024-11-10 05:47:05 字数 925 浏览 0 评论 0原文

我意识到这不一定是最明智的方法，但现在我的好奇心很活跃，我很好奇如何做到这一点。

我在 Rails 项目中有一个模型。我们将其称为“交易”。每个 ActiveRecord 和所有这些很酷的东西都在数据库中定义了诸如 UPDATED_AT 之类的列，这些列成为 Deal 上的方法： deal.updated_at => '04/19/1966 3:15am'

假设我想要有一些方法来告诉我星期几，而不是整个日期和时间。我意识到 DateTime 类上有方法，所以我可以这样做

  deal.updated_at.day_of_week => 'Monday' (*)

，但是如果我只想

  deal.updated_day => 'Monday'

写在 deal.rb 中

  def update_day
    self.updated_at.day_of_week
  end

怎么办？

但是，如果我希望它始终具有可用于添加到模型中的任何日期列的方法，该怎么办？

我在那里看到了define_method（一些在StackOverflow上）。所以我明白了。但我想在 ActiveRecord 发挥其魔力之后立即调用它，对吧？因此，如果我的 Deal 模型有updated_at、created_at、offered_at 和suitable_at，我会希望为每一个都匹配方法。更重要的是，如果另一个开发人员添加了一个名为 Cammed_at 的列，我希望与 Cammed_at 方法一起创建 Cammed_day 。

我该怎么做呢？

谢谢。

(*) 呃，或者类似的事情，我总是查看那个电话。

原文

I realize this is not necessarily the smartest way to do this, but now my curiosity is active and I am curious how to do it.

I have a model in the Rails project. We'll call it Deal. Per ActiveRecord and all that cool stuff there are columns defined in the database like UPDATED_AT and those become methods on Deal: deal.updated_at => '04/19/1966 3:15am'

Say I wanted to instead have methods that told me the day of the week rather than the whole date and time thing. I realize there are methods ON the DateTime class so I can do

  deal.updated_at.day_of_week => 'Monday' (*)

but what if I just wanted

  deal.updated_day => 'Monday'

I can write in deal.rb

  def update_day
    self.updated_at.day_of_week
  end

Got it.

But what if I wanted it to ALWAYS have the method available for ANY date column that was added to the model?

I saw define_method out there (some here on StackOverflow). So I understand that. But I would want to call it right after ActiveRecord did its magic, right? So if my Deal model had updated_at, created_at, offered_at and lawsuit_at I would want matching methods for each one. More importantly, if another developer came and added a column called scammed_at I would want scammed_day created along with the scammed_at method.

How would I do that?

Thanks.

(*) Uh, or something like that, I always look that call up.

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童话里做英雄 2024-11-17 05:47:05

我想像下面这样的东西应该可以解决问题。在您的模型中：

# looping through all model's columns
self.columns.each do |column|
  #if column's name ends with "_at"
  if column.name =~ /_at$/
    #create method like "udpated_day" 
    define_method "#{column.name[0..-4]}_day" do
      self.send(column.name).day_of_week
    end
  end
end

但这意味着每一列都有一个有效的 day_of_week 方法...

好吧，我想您明白了。请随时询问详情

I guess something like the following should do the trick. In your model:

# looping through all model's columns
self.columns.each do |column|
  #if column's name ends with "_at"
  if column.name =~ /_at$/
    #create method like "udpated_day" 
    define_method "#{column.name[0..-4]}_day" do
      self.send(column.name).day_of_week
    end
  end
end

But it implies every column has a valid day_of_week method...

Well you get the idea I think. Don't hesitate to ask for details

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