Get terms that don't belong to current post with a shortcode

Question

Is it possible to retrieve all the terms of a custom hierarchical taxonomy that do not belong to the current post? Perhaps by using wp_get_post_terms()? I recently stumbled upon this unusual need.

Basically, if my custom taxonomy contain the terms (term1, term2, term3, etc.), I want to show in the single post page that this post belongs to term1 and term2 but not term3 etc.

EDIT: I am having difficulty implementing this in a shortcode. I have this code:

add_shortcode( 'my-no-terms', 'no_terms_func' );
function no_terms_func() {
    $this_post_terms = get_the_terms( $post->ID, 'my-tax-slug' );
    $exclude = wp_list_pluck( $this_post_terms, 'term_id' );
    $args = array(
        'exclude' => $exclude, 
    );
    $terms = get_terms( 'my-tax-slug', $args );
    foreach ( $terms as $term ) {
        return $term->name;
    }
}

But this is only outputting the first term, not the whole list of terms. Where's the culprit?

Answer 1

Put the term IDs of the current post terms in an array, and pass that as the exclude parameter to the get_terms function.

$this_post_terms = get_the_terms( $post->ID, 'your_custom_tax' );
$exclude = wp_list_pluck( $this_post_terms, 'term_id' );
$args = array(
    'exclude' => $exclude, 
);
$terms = get_terms( 'your_custom_tax', $args );