using update_user_meta to rank users

Question

I'm using a plugin that allows users to vote on posts, I'd like to add each vote that's cast to the authors user_meta so I can rank users the same way I rank posts.

There's a couple of different functions in the plugin that update and save the post_meta.

add_action( 'wp_ajax_nopriv_epicred_vote', 'epicred_vote' );
add_action( 'wp_ajax_epicred_vote', 'epicred_vote' );
    function epicred_vote(){
        global $wpdb, $current_user;

        get_currentuserinfo();

        $wpdb->myo_ip   = $wpdb->prefix . 'epicred';

        $option = (int)$_POST['option'];
        $current = (int)$_POST['current'];

        //if we are locked via IP set the fid variable to be the IP address, otherwise log the member ID
        if(get_option('epicred_ip') == 'yes'){
            $ipAddr = isset($_SERVER['HTTP_X_CLUSTER_CLIENT_IP']) ? $_SERVER['HTTP_X_CLUSTER_CLIENT_IP'] : $_SERVER['REMOTE_ADDR'];
            $fid = "'" . $ipAddr . "'"; 
        }else{
            $fid = $current_user->ID;
        }


        $postid = (int)$_POST['poll'];  

        $query = "SELECT epicred_option FROM $wpdb->myo_ip WHERE epicred_ip = $fid AND epicred_id = $postid";

        $al = $wpdb->get_var($query);


        if($al == NULL){
            $query = "INSERT INTO $wpdb->myo_ip ( epicred_id , epicred_ip, epicred_option) VALUES ( $postid, $fid, $option)";
            $wpdb->query($query);
        }else{
            $query = "UPDATE $wpdb->myo_ip SET epicred_option = $option WHERE epicred_ip = $fid AND epicred_id = $postid";
            $wpdb->query($query);
        }

        $vote = get_post_meta($postid,'epicredvote',true);

            if($option == 1){
                if($al != 1){
                    if($al == -1){
                    $vote = $vote+2;    
                    }else{
                    $vote = $vote+1;
                    }
                }
            }


            if($option == -1){

                if($al != -1){
                    if($al == 1){
                        $vote = $vote-2;
                    }else{
                    $vote = $vote-1;
                    }   
                }   
            }
            update_post_meta($postid,'epicredvote',$vote);


            $response['poll'] = $postid;
            $response['vote'] = $vote;

        echo json_encode($response);

        // IMPORTANT: don't forget to "exit"
        exit;
    }

And

function wpt_save_wpeddit() {

     global $wp, $wpdb, $post;  


    // unhook this function so it doesn't loop infinitely
    remove_action('save_post', 'wpt_save_wpeddit');


    // Is the user allowed to edit the post or page?
    if ( !current_user_can( 'edit_post', $post->ID ))
    return $post->ID;
    // OK, we're authenticated: we need to find and save the data. Make sure we don't add an image every time the post is
    // saved as a draft - so keep track of the external URL in a custom field.


        $vote = get_post_meta($post->ID,'epicredvote',true);
        $rank = get_post_meta($post->ID,'epicredrank',true);

        if($vote == ""){
            $vote = 0;
        }
        if($rank == ""){
            $rank = 0;
        }

        update_post_meta($post->ID, 'epicredvote', $vote );
        update_post_meta($post->ID,'epicredrank',$rank);


    add_action('save_post', 'wpt_save_wpeddit');

}

Then my goal would be to use something like this in order to rank the users:-

EDIT:- loop I'm using to output users/scores.

 <?php


                        $args = array(
                            'meta_key' => 'epicredvote',
                            'orderby'  => 'meta_value',
                            'order'    => 'DESC',
                            'number' => 10,

                        );

                        add_action( 'pre_user_query', 'wpse_149342_pre_user_query' );

                        $user_query = new WP_User_Query(  $args );

                        // User Loop
                        if ( ! empty( $user_query->results ) ) {
                            foreach ( $user_query->results as $user ) {
                                echo '<p>' . $user->display_name . '</p>';
                               echo '<span>' . $user->epicredvote . '</span>'; 
                            }
                        } else {
                            echo 'No users found.';
                        }
                    ?>

So one vote on a post = one vote for that user essentially.

Possible, or am I completely off track here?

Answer 1

It looks like the plugin is using the update_post_meta function, which in turn uses the update_metadata function which includes the action hooks update_postmeta and updated_postmeta which fire immediately before and after the post meta is stored to the database. You could hook into one of these to update the user meta of the author of the post. Pseudo code:

add_action( 'update_postmeta', 'wpse155265_update_user_vote', 10, 4 );
function wpse155265_update_user_vote( $meta_id, $object_id, $meta_key, $meta_value ) {
  $post = get_post( $object_id );
  $user_id = $post->post_author;
  $votes = (int) get_user_meta( $user_id, 'epicredvote', true );
  $votes++;
  update_user_meta( $user_id, 'epicredvote', $votes );
}

Edit:

As noted, the above does not take into consideration whether the post meta update is a vote up or down. Revised code below; we'll compare the value of the post meta, old versus new, to determine if the user's meta should be increased or decreased.

add_action( 'update_postmeta', 'wpse155265_update_user_vote', 10, 4 );
function wpse155265_update_user_vote( $meta_id, $object_id, $meta_key, $meta_value ) {
  $post = get_post( $object_id );
  $user_id = $post->post_author;
  $meta_value_old = get_post_meta( $object_id, 'epicredvote', true );
  $votes = (int) get_user_meta( $user_id, 'epicredvote', true );
  ( $meta_value > $meta_value_old ) ? $votes++ : $votes--;
  update_user_meta( $user_id, 'epicredvote', $votes );
}

Another approach that occurred to me just now would be to only calculate the user's votes when ranking users, rather than storing their votes in a meta. Loop through all users from get_users and for each one, calculate their total votes, storing each user into an array with their total as the key, sort the array by vote totals using ksort and then loop through the array to output your ranked list. Running WP_Query for every user might be a bit intense, though. Perhaps there's a single SQL statement that can be put together that will actually return all users sorted by their vote total - but I'd have to fiddle with it to see if that's possible.

Edit:

Here's a single SQL that will calculate and rank your users. Plug this into $wpdb as needed:

global $wpdb;
$results = $wpdb->get_results(
  "
    SELECT u.display_name as name,
    ( SELECT SUM(pm.meta_value)
      FROM wp_posts p, wp_postmeta pm
      WHERE p.post_author = u.ID
      AND p.post_status LIKE 'publish'
      AND pm.meta_key = 'epicredvote'
      AND p.ID = pm.post_id ) as votes
    FROM wp_users u
    ORDER BY votes DESC
  "
);
foreach ( $results as $result ) {
  echo "{$result->name}: {$result->votes} votes<br>";
}