Question

新手问题。我有以下型号：

class Asset < ActiveRecord::Base
  belongs_to :assetable, :polymorphic => true
  #paperclip
  has_attached_file :asset, 
    :hash_secret => "my-secret",
    :url => "/images/:hash_:basename_:style.:extension",
    :path => UPLOAD_PATH + "/:hash_:basename_:style.:extension",
    :styles => { :medium => "300x300>", :thumb => "75x75>"  

    }
end

class Location < ActiveRecord::Base
    has_many :assets, :as => :assetable, :dependent => :destroy
end

class MenuItem < ActiveRecord::Base
    has_many :assets, :as => :assetable
end

我的资产有一个名为description的属性。如果assetable_type是“MenuItem”并且描述为nil，我希望描述是关联的menu_item的主体。我该怎么做？

THX

Answer 1

class Asset < ActiveRecord::Base
    before_save :set_description

    private

    def set_description
        self.description ||= assetable.body if assetable.is_a?(MenuItem)
    end
end

或修改访问者

def description
    return self[:description] unless self[:description].blank?
    assetable.description if assetable.is_a? MenuItem
end

多态关联和设置资产的默认值

1 个答案: