Search WordPress Users by Name

If you run a WordPress site with a large list of users and have ever needed to search for a specific user (from the Users > All Users admin page) there’s a good chance no users were found. The problem is that the default query only searches by nicename (username) and email address. However, if you need to search by first name, last name, or a custom user meta field, the default search query is all but useless. Thankfully, the Improved user search in backend plugin fixes this shortcoming, but unfortunately this plugin is outdated and won’t work if you’re running PHP 5.5 and WordPress 3.9 or higher.

So, I’ve gone ahead and created my own user query filter to fix the problem, and included some additional functionality to improve the usefulness of the user search.

<?php

/**
* user_search_by_multiple_parameters
* 
* Modifies the wp_user_query to allow for User searching (within the WordPress dashboard > Users > All Users) by:
*	first_name
*	last_name
*	nickname
*	any other custom meta_key added to user profiles (manually or through something like Advanced Custom Fields)
*
* @param    object  $wp_user_query  a WordPress query object
*
* @return   object	$wp_user_query  a modified version of the WordPress query object parameter
*/
function user_search_by_multiple_parameters($wp_user_query) {
    if (false === strpos($wp_user_query->query_where, '@') && !empty($_GET["s"])) {
        global $wpdb;

        $user_ids = array();
        $user_ids_per_term = array();

		// Usermeta fields to search
		$usermeta_keys = array('first_name', 'last_name', 'nickname');

		$query_string_meta = "";
		$search_terms = $_GET["s"];
		$search_terms_array = explode(' ', $search_terms);
		
		// Search users for each search term (word) individually
		foreach ($search_terms_array as $search_term) {
			// reset ids per loop
			$user_ids_per_term = array();
			
			// add all custom fields into the query
			if (!empty($usermeta_keys)) {
				$query_string_meta = "meta_key='" . implode("' OR meta_key='", $wpdb->escape($usermeta_keys)) . "'";
			}

			// Query usermeta table
            $usermeta_results = $wpdb->get_results($wpdb->prepare("SELECT DISTINCT user_id FROM $wpdb->usermeta WHERE (" . $query_string_meta . ") AND LOWER(meta_value) LIKE '%%%s%%'", $search_term));

            foreach ($usermeta_results as $usermeta_result) {
	            if (!in_array($usermeta_result->user_id, $user_ids_per_term)) {
                	array_push($user_ids_per_term, $usermeta_result->user_id);
                }
            }
			
			// Query users table
            $users_results = $wpdb->get_results($wpdb->prepare("SELECT DISTINCT ID FROM $wpdb->users WHERE LOWER(user_nicename) LIKE '%%%s%%' OR LOWER(user_email) LIKE '%%%s%%' OR LOWER(display_name) LIKE '%%%s%%'", $search_term, $search_term, $search_term));

            foreach ($users_results as $users_result) {
                if (!in_array($users_result->ID, $user_ids_per_term)) {
                    array_push($user_ids_per_term, $users_result->ID);
                }
            }
            
            // Limit results to matches of all search terms
            if (empty($user_ids)) {
	            $user_ids = array_merge($user_ids, $user_ids_per_term);
            } else {
                if (!empty($user_ids_per_term)) {
                    $user_ids = array_unique(array_intersect($user_ids, $user_ids_per_term));
                }
            }
        }
		
		// Convert IDs to comma separated string
        $ids_string = implode(',', $user_ids);

		if (!empty($ids_string)) {
			// network users search (multisite)
			$wp_user_query->query_where = str_replace("user_nicename LIKE '" . $search_terms . "'", "ID IN(" . $ids_string . ")", $wp_user_query->query_where);
			
			// site (blog) users search
            $wp_user_query->query_where = str_replace("user_nicename LIKE '%" . $search_terms . "%'", "ID IN(" . $ids_string . ")", $wp_user_query->query_where);
            
            // network/site users search by number (WordPress assumes user ID number)
            $wp_user_query->query_where = str_replace("ID = '" . $search_terms . "'", "ID = '" . $search_terms . "' OR ID IN(" . $ids_string . ")", $wp_user_query->query_where);
		}
    }

    return $wp_user_query;
}
add_action('pre_user_query', 'user_search_by_multiple_parameters');

?>

This can simply be dropped into your theme’s functions.php file, or can be used to create a plugin. It will work as is, but if you have custom user meta fields, possibly added using Advanced Custom Fields, you can simply add the field key to the $usermeta_keys array to include it in the user query.