A change in URL slug in database returns 404, how can I do auto-redirect?

Question

I have a huge blog with over 10K posts and a lot of posts with some adult keywords in titles, urls, content and tags. I am trying to remove all adult ones with "search and replace" plugin. It works fine, but the problem is the url slugs also changes if there is a bad keyword in the url and the original url becomes 404.

For example, http://www.domain.com/adult-keyword-url changes to http://www.renamed-keyword-url which is fine, but the adult keyword url is now 404 and does not redirect to renamed url. Is there a way that the original url automatically do 301 redirects to the changed url?

I tried using the redirection plugin too which claims to auto-redirect such posts. It works fine only when you manually change the url slug of a post and update a post. But it does not work in this case when you are updating a lot of posts by directly changing the database with search and replace plugin.

Answer 1

If you look in the database in the $wpdb->postmeta table you will see a meta_key named _wp_old_slug. That is how WordPress tracks slug changes. By editing the database directly you bypassed the mechanisms that create that postmeta entry.

You never want to edit the database directly if you can use WordPress Core functions instead. Attempting that kind of shortcut only causes problems, expecially if you don't have a deep and thorough grasp of WordPress internals.

What you want to do instead is run a function similar to this one from another answer:

function fix_post_slugs() {
  $posts = new WP_Query(array('post_type'=>'book'));
  if (empty($posts->posts)) return false;
  foreach ($posts->posts as $p) {
    wp_update_post((array)$p);
  }
}
fix_post_slugs();

In your case, this will do it I believe:

function fix_post_slugs() {
  $posts = new WP_Query(array('post_type'=>'post','post_per_page' =>3));
  if (empty($posts->posts)) return false;
  foreach ($posts->posts as $p) {
    // edit below to search and replace as needed
    $p->post_title = str_replace(' ','+',$p->post_title);
    $p->post_name = sanitize_title_with_dashes($p->post_title);
    wp_update_post((array)$p);
  }
}
fix_post_slugs();

I don't know if you are in a position to back up and do that. If not, you will have to manually map your old slugs to the new ones.