Custom post types & Pages hierarchy - Error 404

Question

I've defined two custom post types:

• Theme
• Fiche

I've also 7 pages using a defined rubrique template: (template-rubrique.php)

Both my Theme and Fiche have an ACF post-object field.

• The Theme ACF post-object field is used to target a Rubrique.
• The Fiche ACF post-object field is used to target a Theme.

---

I'd like my CPTS URL to be in the following format: example.com/myRubriqueName/myThemeName/myFicheName.

myRubriqueName is a Page, while myThemeName and myFicheName are CPT.

Up to now, all my fiche and theme posts URL are well generated, but they end up in a 404 page. Furthermore, my posts and pages are redirected to the front-page.

I'm using the code from this post, which I tried to adjust to my situation.

---

CPTs registering:

register_post_type('theme', array(
    'labels' => array(
        'name' => 'Thèmes',
        'singular_name' => 'Thème',
    ),
    'public' => true,
    'has_archive' => false,
    'hierarchical' => false,
    'menu_icon' => 'dashicons-art',
    'rewrite' => array(
        'slug' => '%rubrique%', // %rubrique% is used as placeholder
        'with_front' => false
    )
));


register_post_type('fiche', array(
    'labels' => array(
        'name' => 'Fiches',
        'singular_name' => 'Fiche',
    ),
    'public' => true,
    'has_archive' => false,
    'hierarchical' => false,
    'menu_icon' => 'dashicons-clipboard',
    'rewrite' => array(
        'slug' => '%rubrique%/%theme%', // %rubrique%/%theme% is used as placeholder
        'with_front' => false
    ),
));

Rewrite rules

function fiche_rewrite() {

    add_rewrite_tag(
        '%theme%',
        '([^&]+)',
        'theme='
    );
}
add_action( 'init', 'fiche_rewrite' );


function theme_rewrite() {

    add_rewrite_tag(
        '%rubrique%',
        '([^&]+)',
        'rubrique='
    );
}
add_action( 'init', 'theme_rewrite' );

CPT placeholder rewriting

function gpc_custom_post_link_replacements( $post_link, $post ) {

    $cpts = array('theme', 'fiche');

    if ( empty( $post ) || !in_array($post->post_type, $cpts) ) {
        return $post_link;
    }

    switch ($post->post_type) {
        case 'fiche':
            $theme_id = get_field('fiche-attachment', $post->ID);
            $theme_slug = get_post_field( 'post_name', $theme_id );

            $rubrique_id = get_field('theme-attachment', $theme_id);
            $rubrique_slug = get_post_field('post_name', $rubrique_id);

            if ( !empty( $theme_slug ) && !empty( $rubrique_slug ) ) {
                $post_link = str_replace('%rubrique%', $rubrique_slug, $post_link );
                $post_link = str_replace('%theme%', $theme_slug, $post_link );
            }

            break;

        case 'theme':

            $rubrique_id = get_field('theme-attachment', $post->ID);
            $rubrique_slug = get_post_field('post_name', $rubrique_id);

            if ( !empty( $rubrique_slug ) ) {
                $post_link = str_replace('%rubrique%', $rubrique_slug, $post_link );
            }

            break;

    }

    return $post_link;
}
add_filter( 'post_type_link', 'wpc_custom_post_link_replacements', 9, 2 );

Mismatched related posts redirecting

function custom_post_redirects() {

    global $post, $wp_query;
    $redirect_to = get_home_url();

    if( ! is_singular( 'fiche' ) && ! is_singular('theme') ) {
        return;
    }


    if( is_singular('fiche') ) {
        $given_slug = $wp_query->get( 'theme' );
        $expected_theme = get_field('field-attachment', $post->ID );

        if( empty( $given_slug ) || empty( $expected_theme ) ) {
            wp_redirect( $redirect_to );
            exit();
        }

        $expected_slug = get_post_field( 'post_name', $expected_theme );

        if( $given_slug !== $expected_slug ) {
            wp_redirect( $redirect_to );
            exit();
        }
    }

    else if( is_singular('theme' ) ) {
        $given_slug = $wp_query->get( 'rubrique' );
        $expected_rubrique = get_field('theme-attachment', $post->ID);

        if( empty( $given_slug ) || empty( $expected_theme ) ) {
            wp_redirect( $redirect_to );
            exit();
        }

        $expected_slug = get_post_field( 'post_name', $expected_rubrique );

        if( $given_slug !== $expected_slug ) {
            wp_redirect( $redirect_to );
            exit();
        }
    }

}
add_action( 'template_redirect', 'custom_post_redirects' );

Answer 1

'Flush' the permalinks.

a 404 when one has added code that creates or affects custom post types often is solved by simply 'flushing' the permalinks. One can do this manually by visiting settings -> permalinks.
https://typerocket.com/flushing-permalinks-in-wordpress/.

It's an 'expensive' operation, so it is suggested not to include the code to do it https://codex.wordpress.org/Function_Reference/flush_rewrite_rules, but just do it once manually.