在rails app错误中附加了pdf

Question

我正在实施和mvc rails app， 我可以将pdf附加到电子邮件并发送 。 但是当我试图从我的Gmail中打开附件时，浏览器会显示：

  

无法加载PDF文档

控制器：

def update
 if !params[:attachment].nil? && !params[:attachment].blank?
   @file = Tempfile.new([params[:attachment], '.pdf']) 
   s = StringIO.new(params[:attachment])
   def s.original_filename; "Answer.pdf"; end
   @file_name = s.original_filename
 else
    @file = ""
    @file_name = ""
 end 
 respond_to do |format|
      if @study_request.update(study_request_params)
        format.html { redirect_to study_requests_path, notice: 'Answer Sended.' }
        format.json { render :show, status: :ok, location: @study_request }
        enviar()
      else
        format.html { render :edit }
        format.json { render json: @study_request.errors, status: :unprocessable_entity }
      end
 end
end
def enviar()
            mail = StudyRequestMailer.new_analysis(@study_request,@file_name,@file)
            mail.deliver_now
end

查看：

<div class="ui form">
  <%= form_with(model: study_request, local: true) do |form| %>
        .
        .
        .
        .
        .
   <div class="field">
     <%= file_field_tag :attachment,:class=>"form-control btn-metis-7 btn-file" %>
     <%= form.submit "Send Mail", :class => 'ui fluid large teal submit button' %>
   </div>
  <%end%>
</div>

邮件程序：

class StudyRequestMailer < ApplicationMailer
  def new_analysis(studyRequest,file_name,file)
    @studyRequest = studyRequest
    if file != ""
      attachments[file_name] = File.read(file)
    end
    mail to: @studyRequest.email, subject: "Answer"
  end
end