如何驗證嵌套模型中的附件？

Question

我有一個設計模型，在兩個關聯（full_image和預覽）中有兩個回形針附件。 我希望僅當full_image和Preview都具有有效文件但似乎無法使其工作時才能保存設計。 現在這是我期望的工作方式，但是當我提交表單時，它不僅不驗證附件。

class Design < ActiveRecord::Base

  has_one :full_image, :as => :assetable, :class_name => "FullImage", :dependent => :destroy
  has_one :preview   , :as => :assetable, :class_name => "Preview"  , :dependent => :destroy

  accepts_nested_attributes_for :full_image, :preview
  validates_associated :preview, :full_image

end

class Asset < ActiveRecord::Base
    belongs_to :assetable, :polymorphic => true
    delegate :url, :to => :attachment
end

class FullImage < Asset
    has_attached_file :attachment
    validates_attachment_presence :attachment
end

class Preview < Asset
    has_attached_file :attachment
    validates_attachment_presence :attachment
end

有人可以建議我應該做什么嗎？

Answer 1

嘗試：在關聯的模型中驗證：attachment，：presence => true而不是validates_attachment_presence

Answer 2

這是我如何工作的

class Design < ActiveRecord::Base

  has_one :full_image, :as => :assetable, :class_name => "FullImage", :dependent => :destroy
  has_one :preview   , :as => :assetable, :class_name => "Preview"  , :dependent => :destroy

  accepts_nested_attributes_for :full_image, :preview

  validates_presence_of :preview
  validates_presence_of :full_image

end

class Asset < ActiveRecord::Base
    belongs_to :assetable, :polymorphic => true
    delegate :url, :to => :attachment
end

class FullImage < Asset
    has_attached_file :attachment
end

class Preview < Asset
    has_attached_file :attachment
end