更改虚拟属性时如何关闭回调？

Question

My model has an 'url' virtual parameter with a big amount of data at the link. The same model has a paperclip attachment: so when a new instance is created, it can contain the data for attachment or url-string from where the object should download it. I want to encapsulate all the checking if it is url-based data or the raw one from controller:

@music = @order.build_music(params[:soundtrack])
if @music.save
    format.html { redirect_to edit_order_path(@order) }
    format.js 
else
    format.html {render :action => 'new'}
    format.js
end

I want My music model check if there is a url virtual parameter is set and if it so download it asynchronously:

has_attached_file :soundfile

after_save :check_if_url

def self.downloadSoundtrack(id, url)
    find(id).update_column(:soundfile, open(url))
end

private
    def check_if_url
        if self.url.present?
            Soundtrack.delay.downloadSoundtrack(self.id, self.url)
        end
    end

but update_column does not work with virtual parameters, and I can't use save 'cuz it will fire after_save callback recusivelly. Plz, help, guys!

Answer 1

试试这个，它不会触发回调

Model.where(id: id).update_all(soundfile: open(url))

Answer 2

API文档 ：通过传递validate: false可以跳过save的验证过程。