Meta Box

Temporarily solved it wthis way:

/**
 * Maybe add required span to labels
 */
add_filter( 'rwmb_begin_html', function ( $begin, $field, $meta ) {
 
    if ( is_admin() )
        return $begin;
 
    if ( ! empty ( $field['required'] ) ) {
        $begin = str_replace( '</label>', '<span class="req">*</span></label>', $begin );
    }
 
    return $begin;
}, 10, 3 );

Additional question: Tried to apply this hook only to the frontend submission fields, by using filters/prefixes like rwmb_frontend_begin_html, mb_frontend_begin_html, rwmb_mb_frontend_begin_html but none of them worked.

Mh I'm registering the metaboxes as follows:

add_filter( 'rwmb_meta_boxes', function( $meta_boxes ) { ... }

[mb_frontend_form id="Meta box ID" post_fields="thumbnail"]

Yeah indeed what assumed 😉

Maybe it would be too complicated on a shortcode basis, especially when adding descriptions for multiple fields.

What you would provide a filter loops through all "post_fields". This way we could easily hook into and add a custom description as well as the required attribute mentioned in another ticket.

Here's a piece of "pseudo code":

$post_field = array(
    'key' => 'title,
    'label' => 'Title',
    'description' => '',
    'required' => false
);

The filter could either be applied on every single field or on a array holding all fields which are "activated" through the shortcode.

Hope you got what I mean 🙂