Here's the filters I applied to enable username searching (also does firstname and lastname search). Hope it helps you (wouldn't mind a mention if it does ;) ):
function search_author_join( $join )
{
if( is_search() ) {
global $wpdb;
$join .= "
LEFT JOIN (SELECT ID AS uid, display_name FROM $wpdb->users) AS u ON $wpdb->posts.post_author = u.uid
LEFT JOIN (SELECT user_id AS umid1, meta_value AS first_name FROM $wpdb->usermeta WHERE meta_key='first_name') AS um1 ON $wpdb->posts.post_author = um1.umid1
LEFT JOIN (SELECT user_id AS umid2, meta_value AS last_name FROM $wpdb->usermeta WHERE meta_key='last_name') AS um2 ON $wpdb->posts.post_author = um2.umid2
";
}
return $join;
}
add_filter('posts_join', 'search_author_join');
function search_author_where( $where )
{
if( is_search() )
{
global $wp_query, $wpdb;
$search_string = $wp_query->query_vars['s'];
$where .= " OR (
(
display_name LIKE '%$search_string%'
OR first_name LIKE '%$search_string%'
OR last_name LIKE '%$search_string%'
)
AND $wpdb->posts.post_type='post'
AND $wpdb->posts.post_status='publish'
)
";
}
return $where;
}
add_filter('posts_where', 'search_author_where');
