Dynamically pull the correct email address from a match

Question

Here's my current function,

 class emailer {
  function notifyHeart($post_ID)  {
    $interests = get_user_meta(get_current_user_id(), 'interests');
    $post = get_post($post_ID);

    foreach($interests as $interest) {
      if(has_tag($interest, $post)) {
        $to = get_the_author_meta( 'user_email', get_current_user_id() );  
        $email = $to;
        mail($email, "An article about Heart", 'A new post has been published!');
        break;
      }
    }
  }
}
add_action('publish_post', array('emailer', 'notifyHeart'));

So far it only works with one user, the other user isn't receiving an email when there's a tag from post that match their interest.

Ideally, I would like to retrieve an email only when a user's $interest matches a tag from a post, then the appropriate email address will be selected and sent.

Answer 1

Who should retrieve an email? The hook 'publish_post' is triggered when an author puiblish a post. So current user == post author.

I assume you would do that: If Buddy-A publish a post and Buddy-B is logged in at the same time, than Buddy-B should retrieve an email that Buddy-A published a post (which maybe interrest Buddy-B).

If I hit the nail and this is it what you want to do, forget it. WordPress have no centralized user management. You need a plugin ( see List of logged in users ) to get a list of all users currently logged in. Call your function for every user in the list and check if a interest match a post tag.