当作品中没有附件时，下载报错

app/controllers/zipdown_controller.rb

@@ -30,8 +30,7 @@ class ZipdownController < ApplicationController
       if file_count > 0
         zipfile = zip_bid bid
       else
-        render file: 'public/no_file_found.html'
-        return
+        zipfile = {:message => "no file"}
       end
     elsif params[:obj_class] == "HomeworkCommon"
       homework = HomeworkCommon.find params[:obj_id]
@@ -41,8 +40,7 @@ class ZipdownController < ApplicationController
       if file_count > 0
         zipfile = zip_homework_common homework
       else
-        render file: 'public/no_file_found.html'
-        return
+        zipfile = {:message => "no file"}
       end
     else
       logger.error "[ZipDown#assort] ===> #{params[:obj_class]} unKown !!"

public/javascripts/application.js

@@ -901,24 +901,30 @@ $(function(){
     $('#download_homework_attachments').bind('ajax:complete', function (event, data, status, xhr) {
         if(status == 'success'){
             var res = JSON.parse(data.responseText);
-            if(res.length<1){
-                return;
+            if(res.length == null){
+                alert("该作业没有任何附件可下载");
             }
-            if(res.length==1){
-                location.href = '/zipdown/download?file='+res[0].file;return;
+            else if(res.length<1){
+                return;
             }
-            document.getElementById('light').style.display='block';
-            $container = $('#light .upload_box_ul');
-            $container.empty();
-            for(var i = 0; i <res.length; ++i){
-                var des = '';
-                if(res.count > 1){
-                    des = '第'+res[i].index+'-'+(res[i].count+res[i].index-1)+'个学生的作品下载';
-                } else {
-                    des = '第'+res[i].index+'个学生的作品下载';
+            else
+            {
+                if(res.length==1){
+                    location.href = '/zipdown/download?file='+res[0].file;return;
                 }
-                $('<li><span class="upload_box_span" >'+(i+1)+'.</span> <a href="/zipdown/download?file='+res[i].file+'">'+des+'</a><span class="c_grey">&nbsp;&nbsp;（共'+res[i].size+'M）</span> </li>').appendTo($container);
+                document.getElementById('light').style.display='block';
+                $container = $('#light .upload_box_ul');
+                $container.empty();
+                for(var i = 0; i <res.length; ++i){
+                    var des = '';
+                    if(res.count > 1){
+                        des = '第'+res[i].index+'-'+(res[i].count+res[i].index-1)+'个学生的作品下载';
+                    } else {
+                        des = '第'+res[i].index+'个学生的作品下载';
+                    }
+                    $('<li><span class="upload_box_span" >'+(i+1)+'.</span> <a href="/zipdown/download?file='+res[i].file+'">'+des+'</a><span class="c_grey">&nbsp;&nbsp;（共'+res[i].size+'M）</span> </li>').appendTo($container);
 
+                }
             }
         }
     });