博客回复后，该博客的更新时间为当前时间

app/controllers/blog_comments_controller.rb

@@ -127,6 +127,7 @@ class BlogCommentsController < ApplicationController
     @blogComment.title = "RE: #{@article.title}" unless params[:blog_comment][:title]
     @article.children << @blogComment
     @article.save
+    # @article.update_attribute(:updated_on, @blogComment.updated_on)
     @user_activity_id = params[:user_activity_id]
     user_activity = UserActivity.where("act_type='BlogComment' and act_id =#{@article.id}").first
     if user_activity

app/models/blog_comment.rb

@@ -18,6 +18,7 @@ class BlogComment < ActiveRecord::Base
 
   after_save :add_user_activity
   after_update :update_activity
+  after_create :update_parent_time
   before_destroy :destroy_user_activity
 
   scope :like, lambda {|arg|
@@ -64,6 +65,11 @@ class BlogComment < ActiveRecord::Base
     (user && user.logged? && (self.author == user) ) || user.admin?
   end
 
+  def update_parent_time
+    if !self.parent.nil?
+      self.root.update_attribute(:updated_on, self.updated_on)
+    end
+  end
   def project
   end
 end