Rails 4 Wick_pdf发送附加空白pdf

Question

我在我的Rails 4应用程序中使用wick_pdf将几个html模板转换为pdf文件。然后我将这些pdf附加到出站电子邮件中。电子邮件和pdf正在正确发送，但还有一个空白的pdf（有时不完全）与我想要的pdf一起发送。我在下面附上了我的代码。如果您有任何建议，请告诉我。

def approval_notification(id)
    @user = User.find(id)

    esign = WickedPdf.new.pdf_from_string(render_to_string pdf: "esign", template: "disclosures/pdfs/esign_pdf.html.erb", formats: :html, encoding: "UTF-8") 

    mail(:to => @user.email, :subject => 'Congratulations! You have been approved!') do |format|
       format.html 
       format.pdf do
          attachments['Electronic_Signature.pdf'] = esign
       end
    end
end

更新

好吧，我设法解决了这个问题。我仍然不完全明白什么是错的所以请解释一下你是否知道。修改后的代码如下：

def approval_notification(id)
    @user = User.find(id)

    esign = WickedPdf.new.pdf_from_string(render_to_string pdf: "esign", template: "disclosures/pdfs/esign_pdf.html.erb", formats: :html, encoding: "UTF-8") 

    attachments['Electronic_Signature.pdf'] = esign

    mail(:to => @user.email, :subject => 'Congratulations! You have been approved!') 
 end