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@unosk

Railsで変更不可な導出カラムを設定する

More than 5 years have passed since last update.

例えば、こんなモデル

Circle:円形
 - radius: 半径
 - square: 面積 # このカラムは半径から導出したいので、直接変更できないようにしたい
class Circle < ActiveRecord::Base
  def radius=(radius)
    super
    self[:square] = radius*radius*Math::PI
  end

  def square=(square)
  end
end

ポイント

  • squareのセッターメソッドを無効化
  • radiusのセッターメソッドでsquareを計算
  • squareにアクセスするにはself[:square]を用いる
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unosk
東京でスタートアップのエンジニアやってます。
neuro
二次交通に特化したモビリティプラットフォームRYDEの企画運営しています。

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7
Help us understand the problem. What is going on with this article?