Custom filter in users list

[sebastian.pisula]

I have example code:

<?php

function admin_users_filter( $query ){
        global $pagenow,$wp_query;

        if ( is_admin() && $pagenow=='users.php' && isset($_GET['abc']) && $_GET['abc'] != '') {
                $query->search_term = urldecode($_GET['abc']);

                global $wpdb;

                if (!is_null($query->search_term)) {

                        $query->query_from .= " INNER JOIN {$wpdb->usermeta} ON " .
                                              "{$wpdb->users}.ID={$wpdb->usermeta}.user_id AND " .
                                              "{$wpdb->usermeta}.meta_key='meta_key_name_here' AND "."{$wpdb->usermeta}.meta_value LIKE '%{$query->search_term}%'";

                }
        }
}

add_filter( 'pre_user_query', 'admin_users_filter' );


add_action( 'restrict_manage_users', 'restrict_abc_manage_list' );
function restrict_abc_manage_list()
{
        ?>
        <select name="abc" style="float: none;">
                <option value=""><?php _e('Filter By College', 'baapf'); ?></option>
                <option value="1">1</option>
                <option value="2">2</option>
                <option value="3">3</option>

        </select>
        <input id="post-query-submit" class="button" type="submit" value="Filter" name="">
        <?php
}

Source: ​http://stackoverflow.com/a/20520947

But variable "abc" have empty value. WTF?

[ocean90]

Duplicate of #35307.

That's because the select box is added to the bottom of the table too. On a form submit the value of the first select box gets overridden by the value of the second box. [37422] introduces the $which parameter so you can use two different name attributes.

Related: ​[bbpress6061]