Wordpress URLs: Add custom taxonomy to permalink structure - Allows you to use the /%name%/ of a custom taxonomy in permalink structures. Be sure to set $taxName and $default variables. Adapted from: https://www.shibashake.com/wp/add-custom-taxonomy-tags-to-your-wordpress-permalinks - Code Snippets Pro

wp_add_custom_taxonomy_to_permalink_structure.php

<?php

// Adapted from: https://www.shibashake.com/wp/add-custom-taxonomy-tags-to-your-wordpress-permalinks

namespace Bs3LfBs;
	
function add_custom_tax_permalink($permalink, $post_id, $leavename) {
	
	// name of the custom taxonomy
	$taxName = 'song';
	// fallback term to use if a post does not have any attached terms
	$default = 'misc';
    
	if (strpos($permalink, "%$taxName%") === FALSE) return $permalink;
     
        // Get post
        $post = get_post($post_id);
        if (!$post) return $permalink;
 
        // Get taxonomy terms
        $terms = wp_get_object_terms($post->ID, $taxName);   
        if (!is_wp_error($terms) && !empty($terms) && is_object($terms[0])) $taxonomy_slug = $terms[0]->slug;
        else $taxonomy_slug = $default;
 
    return str_replace("%$taxName%", $taxonomy_slug, $permalink);
}   

add_filter('post_link', '\Bs3LfBs\add_custom_tax_permalink', 10, 3);
add_filter('post_type_link', '\Bs3LfBs\add_custom_tax_permalink', 10, 3);
 

For Code Snippets Pro - https://codesnippets.pro/
Allows you to use the /%name%/ of a custom taxonomy in permalink structures. Be sure to set $taxName and $default variables.
Adapted from: https://www.shibashake.com/wp/add-custom-taxonomy-tags-to-your-wordpress-permalinks