Output all terms in a custom taxonomy and add a “active” class only to the ones attached to the current post

Question

I want to output all the terms in my custom taxonomy and at the same time add a class to any of these that are attached to the current post.

I'm doing this in a custom shortcode that displays on each single post page.

I've used get_terms() to show all the terms in the taxonomy but I can't work out how to check if each term is attached to the current post.

$terms = get_terms( array(
    'taxonomy' => 'package',
    'hide_empty' => false
) );

if (!empty($terms) && ! is_wp_error( $terms )) {
  echo '<ul>';
  foreach ($terms as $term) {
    echo '<li>' . $term->name . '</li>';
  }  
  echo '</ul>';  
}

Answer 1

how to check if each term is attached to the current post

You can do that using has_term() which defaults to checking on the current post in the main loop, hence you can omit the third parameter (the post ID).

So for example in your case:

$class = has_term( $term->term_id, $term->taxonomy ) ? 'active' : ''; // like this
//$class = has_term( $term->term_id, 'package' ) ? 'active' : '';     // or this

echo '<li class="' . $class . '">' . $term->name . '</li>';