在導軌模型中動態生成示波器

Question

我想動態生成示波器。比方說，我有以下型號：

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 

我們可以更換的scope調用的東西基礎上，不斷POSSIBLE_SIZES？我認爲我違反DRY重複他們。

Answer 1

你可以做

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

，但我個人更喜歡：

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

Answer 2

，你可以做一個循環

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