只有课程里才用到了tag 云，

app/views/files/_tag_yun.html.erb

@@ -1,7 +1,9 @@
+<% if course %>
 <span class="files_tag_icon" >
           <a  title="双击可编辑"
               onclick="search_tag_attachment('<%= search_tag_attachment_course_files_path(course)%>','','<%= @q%>','<%= course.id%>');"
               >全部</a></span>
+<% end %>
 <% unless tag_list.nil?%>
     <% tag_list.each do |k,v|%>
         <% if tag_name && tag_name == k%>