Question

我有一个IncomingEmail模型，其中包含attachments个虚拟属性：

class IncomingEmail < ActiveRecord::Base  
  attr_accessor :attachments
end

我希望将attachments虚拟属性初始化为[]而不是nil，以便我可以这样做：

>> i = IncomingEmail.new
=> #<IncomingEmail id: nil,...)
>> i.attachments << "whatever"

首先将i.attachments设置为[]（换句话说，我希望此虚拟属性默认为空数组而不是nil）

Answer 1

使用after_initialize回调

class IncomingEmail < ActiveRecord::Base  
  attr_accessor :attachments
  def after_initialize
    self.attachments ||= [] # just in case the :attachments were passed to .new
  end
end

初始化虚拟属性

1 个答案: