解决个人博客报500的问题

app/views/blogs/_article.html.erb

@@ -78,7 +78,7 @@
         发帖时间：<%= format_time(activity.created_on) %>
       </div>
       <div class="homepagePostDate fl ml15">
-        更新时间：<%= format_time(UserActivity.where("act_type='#{activity.class}' and act_id =#{activity.id}").first.updated_at) %>
+        更新时间：<%= format_time(activity.updated_on) %>
       </div>
       <div class="cl"></div>
       <div class="homepagePostIntro break_word upload_img list_style maxh360 table_maxWidth" id="activity_description_<%= user_activity_id%>">