附件单独下载报错

app/controllers/attachments_controller.rb

@@ -69,7 +69,7 @@ class AttachmentsController < ApplicationController
     if candown || User.current.admin? || User.current.id == @attachment.author_id
       @attachment.increment_download
       if stale?(:etag => @attachment.digest)
-        convered_file = File.join(Rails.root, "files", "convered_office", a.disk_filename + ".html")
+        convered_file = File.join(Rails.root, "files", "convered_office", @attachment.disk_filename + ".html")
         if File.exist?(convered_file)
           render :text => File.open(convered_file).read
         else
@@ -78,11 +78,9 @@ class AttachmentsController < ApplicationController
             :disposition => 'attachment'    #inline can open in browser
         end
       end
-
     else
       render_403 :message => :notice_not_authorized
     end
-
   rescue => e
     redirect_to "http:  //" + (Setting.host_name.to_s) +"/file_not_found.html"
   end