title: Rails 3: Railscast #167 virtual attribute for creating tags - @user.tags
body: <p>I would like to a tagging system where I can separate the tags by the user's who created them. I followed Railscast #167 about setting up tags using virtual attributes, but that way only lets me call @post.tags to find the tags for a post, but I can't call @user.tags and find all their tags. </p>
  
  <p>How could I augment this so that @user.posts.tag("music") would return all their posts with the tag music?</p>
  
  <p>Thanks for an help or insight into what I'm doing wrong.</p>