Hello,

Please can you take a look at this code if its safe to use. I want to add the (article) pre slug in my blog posts but wordpress does not allow this in the permalink settings without it affectig other custom post types.

Post post type should have (article) pre slug e.g https://www.website.com/article/fdfghfgf/
Advert post type should have (advert) pre slug e.g https://www.website.com/advert/drdrtytf/
Pages should not have any pre slug https://www.website.com/ytrytytyu/

see code below

/**
 * Rewrite WordPress URLs to Include /article/ in Post Permalink Structure
 *
 * @author   Golden Oak Web Design <info@goldenoakwebdesign.com>
 * @license  https://www.gnu.org/licenses/gpl-2.0.html GPLv2+
 */
function np_generate_rewrite_rules( $wp_rewrite ) {
  $new_rules = array(
    '(([^/]+/)*article)/page/?([0-9]{1,})/?$' => 'index.php?pagename=$matches[1]&paged=$matches[3]',
    'article/([^/]+)/?$' => 'index.php?post_type=post&name=$matches[1]',
    'article/[^/]+/attachment/([^/]+)/?$' => 'index.php?post_type=post&attachment=$matches[1]',
    'article/[^/]+/attachment/([^/]+)/trackback/?$' => 'index.php?post_type=post&attachment=$matches[1]&tb=1',
    'article/[^/]+/attachment/([^/]+)/feed/(feed|rdf|rss|rss2|atom)/?$' => 'index.php?post_type=post&attachment=$matches[1]&feed=$matches[2]',
    'article/[^/]+/attachment/([^/]+)/(feed|rdf|rss|rss2|atom)/?$' => 'index.php?post_type=post&attachment=$matches[1]&feed=$matches[2]',
    'article/[^/]+/attachment/([^/]+)/comment-page-([0-9]{1,})/?$' => 'index.php?post_type=post&attachment=$matches[1]&cpage=$matches[2]',		
    'article/[^/]+/attachment/([^/]+)/embed/?$' => 'index.php?post_type=post&attachment=$matches[1]&embed=true',
    'article/[^/]+/embed/([^/]+)/?$' => 'index.php?post_type=post&attachment=$matches[1]&embed=true',
    'article/([^/]+)/embed/?$' => 'index.php?post_type=post&name=$matches[1]&embed=true',
    'article/[^/]+/([^/]+)/embed/?$' => 'index.php?post_type=post&attachment=$matches[1]&embed=true',
    'article/([^/]+)/trackback/?$' => 'index.php?post_type=post&name=$matches[1]&tb=1',
    'article/([^/]+)/feed/(feed|rdf|rss|rss2|atom)/?$' => 'index.php?post_type=post&name=$matches[1]&feed=$matches[2]',
    'article/([^/]+)/(feed|rdf|rss|rss2|atom)/?$' => 'index.php?post_type=post&name=$matches[1]&feed=$matches[2]',
    'article/page/([0-9]{1,})/?$' => 'index.php?post_type=post&paged=$matches[1]',
    'article/[^/]+/page/?([0-9]{1,})/?$' => 'index.php?post_type=post&name=$matches[1]&paged=$matches[2]',
    'article/([^/]+)/page/?([0-9]{1,})/?$' => 'index.php?post_type=post&name=$matches[1]&paged=$matches[2]',
    'article/([^/]+)/comment-page-([0-9]{1,})/?$' => 'index.php?post_type=post&name=$matches[1]&cpage=$matches[2]',
    'article/([^/]+)(/[0-9]+)?/?$' => 'index.php?post_type=post&name=$matches[1]&page=$matches[2]',
    'article/[^/]+/([^/]+)/?$' => 'index.php?post_type=post&attachment=$matches[1]',
    'article/[^/]+/([^/]+)/trackback/?$' => 'index.php?post_type=post&attachment=$matches[1]&tb=1',
    'article/[^/]+/([^/]+)/feed/(feed|rdf|rss|rss2|atom)/?$' => 'index.php?post_type=post&attachment=$matches[1]&feed=$matches[2]',
    'article/[^/]+/([^/]+)/(feed|rdf|rss|rss2|atom)/?$' => 'index.php?post_type=post&attachment=$matches[1]&feed=$matches[2]',
    'article/[^/]+/([^/]+)/comment-page-([0-9]{1,})/?$' => 'index.php?post_type=post&attachment=$matches[1]&cpage=$matches[2]',
  );
  $wp_rewrite->rules = $new_rules + $wp_rewrite->rules;
}
add_action( 'generate_rewrite_rules', 'np_generate_rewrite_rules' );

function np_update_post_link( $post_link, $id = 0 ) {
  $post = get_post( $id );
  if( is_object( $post ) && $post->post_type == 'post' ) {
    return home_url( '/article/' . $post->post_name.'/' );
  }
  return $post_link;
}
add_filter( 'post_link', 'np_update_post_link', 1, 3 );