Wordpress custom post permalinks with taxonomies breaks normal pages

Question

For a project I'm working on I want to achieve the following permalink structure for my posts:

domain.com/special/my-post-slug

where special is a custom taxonomy.

What I did:

• Went to settings > permalinks
• Select the custom option and transformed it to this: /%specials%/%postname%/
• hooked in the following Wordpress hooks like this:

<?php

// in functions.php


add_filter('post_link', 'specials_permalink', 10, 3);
add_filter('post_type_link', 'specials_permalink', 10, 3);

function specials_permalink($permalink, $post_id, $leavename) {

    if (strpos($permalink, '%specials%') === FALSE) {
        return $permalink;
    }

    $post = get_post($post_id);

    if (!$post) {
        return $permalink;
    }

    $terms = wp_get_object_terms($post->ID, 'specials');

    if (!is_wp_error($terms) && !empty($terms) && is_object($terms[0])) {
        $taxonomy_slug = $terms[0]->slug;
    } else {
        $categories = wp_get_post_categories($post_id->ID, array('fields' => 'all'));

        if(isset($categories[0])) {
            $taxonomy_slug = $categories[0]->slug;
        } else {
            $taxonomy_slug = 'general';
        }
    }

    $permalink = str_replace('%specials%', $taxonomy_slug, $permalink);

    return $permalink;
}

This code works just fine, BUT since I added the specials to the permalink structure for my posts, my pages won't load anymore. They all result in a 404. As soon as I remove %specials% from the permalink structure they work again.

While debugging I found out that Wordpress matches my urls as followed:

Request:

fr/my-slug

Query String:

lang=fr&specials=my-slug

Matched Rewrite Rule:

(fr|nl|en)/([^/]+)/?$

Matched Rewrite Query:

lang=fr&specials=my-slug

But it has to be 'pagename' intead of 'specials'. I already tried by remapping some urls and adding custom rewrite rules and stuff like that but I can't find any solution. The weirdest part is that according to the WP Codex the permalink structure is only applied to posts and archive pages, not to pages. My function which is hooked into the link does not get fired when loading the page. But for some reason Wordpress thinks my pages are specials.

I tried to add as much information as possible, but if something is missing pleas ask.

Answer 1

If you change the permalink structur under Settings -> Permalinks, you change it for all post types (I think).

My suggestion: Leave the permalink structure as it is by default (/%postname%/) and add post type checking in your filter function:

function specials_permalink($permalink, $post_id, $leavename) {

    if ( 'post' != get_post_type( $post_id ) ) {
        return $permalink;
    }

    // rest of your code

}