ruby-on-rails - 在 Rails 模型中动态生成范围

Question

我想动态生成作用域。假设我有以下模型:

class Product < ActiveRecord::Base
    POSSIBLE_SIZES = [:small, :medium, :large]
    scope :small, where(size: :small) 
    scope :medium, where(size: :medium) 
    scope :large, where(size: :large) 
end

我们可以用基于 POSSIBLE_SIZES 常量的东西替换 scope 调用吗？我认为我违反了 DRY 以重复它们。

Answer 1

你可以做

class Product < ActiveRecord::Base
  [:small, :medium, :large].each do |s|
    scope s, where(size: s) 
  end
end

但我个人更喜欢:

class Product < ActiveRecord::Base
  scope :sized, lambda{|size| where(size: size)}
end