[...] have tried this method: http://shibashake.com/wordpress-theme/wordpress-permalink-add but I didn’t get that one to work either. The problem is that I just don’t seem to [...]

Is possible create an alias for permalinks of post? if I add a post with poermalink /blog/category/post.html I can add an alias permalink like /blog/category/post/more.html ?
this 2 permalinks must get same post id.

Great articles on custom permalinks. for the site im working on i want links like this

/products/post-type/tax-term/tax-term-child/post-name/

i have been able to get the link structure correct using the post_type_link filter and a foreach() loop on get_the_terms() for that post.

my cpt is registered with slug of ‘products/residential/%res_brands%’
here is that code

`function product_permalink($permalink, $post_id, $leavename) {
if (strpos($permalink, ‘%res_brands%’) === FALSE) return $permalink;

// Get post
$post = get_post($post_id);
if (!$post) return $permalink;

// Get taxonomy terms
$terms = wp_get_object_terms($post->ID, ‘resbrands’);
if (!is_wp_error($terms) && !empty($terms) && is_object($terms[0])) {
$term_count = count($terms);
$i=1;
if($term_count > 1){
foreach( $terms as $term ) {
if (!empty($term) && is_object($term)) $taxonomy_slug .= $term->slug;
if($i slug;
}
}
//else $taxonomy_slug = ‘not-rated’;

return str_replace(‘%res_brands%’, $taxonomy_slug, $permalink);
}`

I am running into trouble coming up with the proper wr_rewrite rules. I have tried several things. Im assuming that because my %res_brands% could be several tags with / is the problem.

Also i am trying to rewrite my function similar to the one used in this article but any help would be great.

Sorry I misunderstood you.

If you want to add %cat_id% to your general permalink structure, i.e. to your post links, then you want to use the post_link hook.

You just need to replace the %cat_id% tag with the proper id. The function would look a lot simpler because you wouldn’t need to construct the whole permalink structure from scratch as I did with the gallery objects above.

Instead your permalink function would just be something like -

function new_permalink($permalink, $post, $leavename) {
  if (strpos($permalink, '%cat_id%') !== FALSE) {
    $cat_id = ...[get cat id from $post]
    $permalink = str_replace('%cat_id%', $cat_id, $permalink);
  }
  return $permalink;
}

Rewrite tag would be something like this -

$wp_rewrite->add_rewrite_tag("%cat_id%", '([0-9]+)', "cat_id=");

Anyway, this is the general idea – you may need to change some things to get it exactly right.