How can I write slugs / permalinks as: custom post type -> custom taxonomy and custom post type -> custom taxonomy (one CPT and many taxo)?

Question

This is my first post, so maybe I'll miss some informations, sorry :bowing.

I have almost the same issue as Paul T did (Permalinks: custom post type -> custom taxonomy -> post), namely :

I have a custom post type called sioban_cpt, which have a custom taxonomy sioban_taxo.

A sioban_cpt can have more than one sioban_taxo.

I would like my urls to route in this manner:

www.mysite.com/sioban_cpt/  =>  archive-sioban-cpt.php
www.mysite.com/sioban_cpt/%sioban_taxo%/ => taxonomy-sioban_taxo.php
**www.mysite.com/sioban_cpt/%postname%/ => single-sioban_cpt.php**

So :

www.mysite.com/sioban_cpt/ => shows all posts with sioban_cpt post-type (this works)
www.mysite.com/sioban_cpt/foo/ => shows all posts with the foo taxonomy(this works)
www.mysite.com/sioban_cpt/bar => shows the indivual post under the sioban_cpt post-type (this doesn't work, it display the error template, although www.mysite.com/sioban_cpt/bar is the shown permalink in the WP admin post edition page)

As Paul T, I try to avoid plugins.

I don't know if a solution is possible, because I want the taxonomy and the posts of the CPT both as descendants of the cpt, and conversely I don't want the posts of the CPT as children of the taxo.

Here is my code in function.php :

/**
 * create new custom taxonomy (has to be called before CPT declaration)
 *
 * @return void
 */
function si0b_ct_year()
{
    /* Property Type */
    $labels = array(
       'name'                       => _x('Years', 'Taxonomy General Name', 'siobanone'),
       'singular_name'              => _x('Year', 'Taxonomy Singular Name', 'siobanone'),
       'menu_name'                  => __('Année de participation', 'siobanone'),
       'all_items'                  => __('Toutes les années', 'siobanone'),
       'new_item_name'              => __('Nouvelle année', 'siobanone'),
       'add_new_item'               => __('Ajouter une nouvelle année', 'siobanone'),
       'edit_item'                  => __('Modifier l\'année', 'siobanone'),
       'update_item'                => __('Actualiser l\année', 'siobanone'),
       'view_item'                  => __('Voir l\année', 'siobanone'),
       'separate_items_with_commas' => __('Separate years with commas', 'siobanone'),
       'add_or_remove_items'        => __('Add or remove years', 'siobanone'),
       'search_items'               => __('Search Years', 'siobanone'),
       'not_found'                  => __('Not Found', 'siobanone'),
       'no_terms'                   => __('No years', 'siobanone'),
       'items_list'                 => __('Years list', 'siobanone'),
       'items_list_navigation'      => __('Years list navigation', 'siobanone'),
   );
    $rewrite = array(
       'slug'                => __('aec-year', 'siobanone'),
       'with_front'          => false
   );
    $args = array(
       'labels'                     => $labels,
       'public'                     => true,
       'show_ui'                    => true,
       'show_admin_column'          => true,
       'show_in_nav_menus'          => true,
       'show_in_quick_edit'         => true,
       'rewrite'                    => $rewrite,
       'show_in_rest'               => true,
       'has_archive'                => true,
   );
    register_taxonomy('aec-year', 'artists', $args);
}

add_action('init', 'si0b_ct_year', 10);

/*To create new custom post type */
function si0b_cpt_artists()
{
    // CPT : artists

    $labels = array(
       'name'                => _x('Artists', 'Post Type General Name', 'siobanone'),
       'singular_name'       => _x('Artist', 'Post Type Singular Name', 'siobanone'),
       'menu_name'           => __('Artists', 'siobanone'),
       'name_admin_bar'      => __('Artists', 'siobanone'),
       'parent_item_colon'   => __('Parent Item:', 'siobanone'),
       'all_items'           => __('All artists', 'siobanone'),
       'add_new_item'        => __('Ajouter nouvel.le artiste', 'siobanone'),
       'add_new'             => __('Ajouter', 'siobanone'),
       'new_item'            => __('New Item', 'siobanone'),
       'edit_item'           => __('Edit Item', 'siobanone'),
       'update_item'         => __('Update Item', 'siobanone'),
       'view_item'           => __('View Item', 'siobanone'),
       'search_items'        => __('Search Item', 'siobanone'),
       'not_found'           => __('Not found', 'siobanone'),
       'not_found_in_trash'  => __('Not found in Trash', 'siobanone'),
   );
    $rewrite = array(
       'slug'                => _x('artistes/%aec-year%', 'siobanone'),
       'with_front'          => false
   );
    $args = array(
       'label'               => __('artists', 'siobanone'),
       'description'         => _x('Artists', 'siobanone'),
       'labels'              => $labels,
       'supports'            => array('title', 'editor', 'thumbnail', 'comments', 'revisions', 'custom-fields', 'page-attributes', 'excerpt'),
       'taxonomies'          => array('aec-year'),
       'hierarchical'        => false,
       'public'              => true,
       'show_ui'             => true,
       'show_in_menu'        => true,
       'menu_position'       => 5,
       'menu_icon'           => 'dashicons-images-alt',
       'show_in_admin_bar'   => true,
       'show_in_nav_menus'   => true,
       'can_export'          => true,
       'has_archive'         => 'artistes',
       'exclude_from_search' => false,
       'rewrite'             => $rewrite,
   );
    register_post_type('artists', $args);
}

add_action('init', 'si0b_cpt_artists', 10);

/**
 *  add a filter to post_type_link to substitute the taxo aec-year in individual CPT artists permalinks
 *
 * @param [type] $post_link
 * @param [type] $post
 * @return void
 */
function si0b_artists_permalinks($post_link, $post)
{
    if (is_object($post) && $post->post_type == 'artists') {
        $terms = wp_get_object_terms($post->ID, 'aec-year');
        if ($terms) {
            return str_replace('%aec-year%', $terms[0]->slug, $post_link);
        }
    }
    return $post_link;
}
add_filter('post_type_link', 'si0b_artists_permalinks', 1, 2);

Thanks for your help...

Answer 1

Thanks to Sally CJ, here is the solution that worked for me :

/*To create new custom taxonomy  */
function si0b_ct_year()
{
    /* Property Type */
    $labels = array(
        'name'                       => _x('Years', 'Taxonomy General Name', 'siobanone'),
        'singular_name'              => _x('Year', 'Taxonomy Singular Name', 'siobanone')
    );

    $rewrite = array(
        'slug'                     => 'artistes',
        'with_front'   => false,
        'hierarchical' => true,
    );

    $args = array(
        'labels'                     => $labels,
        'hierarchical'               => true,
        'public'                     => true,
        'rewrite'                    => $rewrite,
        'show_in_rest'               => true,
    );
    register_taxonomy('aec-year', array('artists'), $args);
}

add_action('init', 'si0b_ct_year', 10);

/*To create new custom post type */
function si0b_cpt_artists()
{
    // CPT : artists

    $labels = array(
        'name'                => _x('Artists', 'Post Type General Name', 'siobanone'),
        'singular_name'       => _x('Artist', 'Post Type Singular Name', 'siobanone'),
    );

    $rewrite = array(
        'slug'                => 'artistes',
        'with_front'          => false,
    );
    $args = array(
        'label'               => __('artists', 'siobanone'),
        'description'         => __('Artists', 'siobanone'),
        'labels'              => $labels,
        'taxonomies'          => array('aec-year', 'post_tag'),
        'hierarchical'        => true,
        'public'              => true,
        'has_archive'         => true,
        'exclude_from_search' => false,
        'publicly_queryable'  => true,
        'query_var'           => 'artists',
        'rewrite'             => $rewrite,
        'show_in_rest'               => true,
    );
    register_post_type('artists', $args);
}

add_action('init', 'si0b_cpt_artists', 10);

/**Allow this :
 * www.mysite.com/sioban_cpt/foo/ => shows all posts with the foo taxonomy
 * www.mysite.com/sioban_cpt/bar => shows the indivual post under the sioban_cpt post-type
**/
function si0b_parse_request( $wp ) {
    $path      = 'artistes'; // rewrite slug; no trailing slashes
    $taxonomy  = 'aec-year'; // taxonomy slug
    $post_type = 'artists';  // post type slug

    if ( preg_match( '#^' . preg_quote( $path, '#' ) . '/#', $wp->request ) &&
        isset( $wp->query_vars[ $taxonomy ] ) ) {
        $slug = $wp->query_vars[ $taxonomy ];
        $slug = ltrim( substr( $slug, strrpos( $slug, '/' ) ), '/' );

        if ( ! term_exists( $slug, $taxonomy ) ) {
            $wp->query_vars['name']       = $wp->query_vars[ $taxonomy ];
            $wp->query_vars['post_type']  = $post_type;
            $wp->query_vars[ $post_type ] = $wp->query_vars[ $taxonomy ];
            unset( $wp->query_vars[ $taxonomy ] );
        }
    }
}
add_action( 'parse_request', 'si0b_parse_request' );