Change the author posts link using custom user metadata

Question

I am trying to use a custom value to be used in the author posts URL instead of the user_nicename which defaults to user_login in the pretty permalink structure. So far I managed to do that but now the new URL /author/custom_user_nicename generate a 404 error while the old one /author/user_login still works. The code I used in theme functions.php file:

add_filter('author_link', 'update_author_link',10,2);
function update_author_link($link,$author_id) {
    if (FALSE === strpos($link, '?author=')) { // only if pretty permalinks used
        $position = strrpos($link, '/');
        if (strlen($link) == $position + 1) { // check and remove trailing slash
            $link = untrailingslashit($link);
            $position = strrpos($link, '/');
        }
        $link = substr($link, 0, $position+1);
        $link = $link . get_the_author_meta('custom_author_nicename', $author_id);
        return user_trailingslashit($link);
    }
    return $link;
}

I tried to flush the rewrite rules by going to settings -> permalinks and save but that did work as well. do I need to update or modify anything else for the new author URL to work? Thanks.

Answer 1

You'll need to add a rewrite rule as well as the filter you have written. At the moment your filter only changes what is output when the author_link function is called, not WordPress' permalink structure.