修改当作业没有附件时老师能打包下载一个空包的问题

app/controllers/zipdown_controller.rb

@@ -21,7 +21,13 @@ class ZipdownController < ApplicationController
   def assort
     if params[:obj_class] == "Bid"
       bid = Bid.find params[:obj_id]
-      zipfile = zip_bid bid
+      file_count = 0
+      bid.homeworks.map { |homework| file_count += homework.attachments.count}
+      if file_count > 0
+        zipfile = zip_bid bid
+      else
+        render file: 'public/no_file_found.html'
+      end
     else
       logger.error "[ZipDown#assort] ===> #{params[:obj_class]} unKown !!"
     end