如何在wordpress循环中显示当前帖子自定义分类名称？

I am currently building a Wordpress site and I am encountering some difficulty with the following..

I am trying to dynamically add a class to a HTML element by displaying the custom taxonomy name of the current post type, to use as the class name. This is all being done within a Foreach loop.

My code is as follows

<?php
$args = array( 'posts_per_page' => -1,  'post_type' => 'staff', 'orderby' => 'menu_order',
    'order'   => 'DESC');
$myposts = get_posts( $args );
foreach ( $myposts as $post ) : setup_postdata( $post ); ?>

<?php $terms = wp_get_post_terms( $post_ID, 'department' ); ?>
<?php global $post; $terms = wp_get_post_terms( $post->ID, 'department'); ?>

<div class="grid-item  <?php echo $term->slug; ?> ">
<div class="staff-box">
    <?php the_post_thumbnail('staff-member'); ?>
    <a href="<?php echo the_permalink(); ?>">
        <p class="staff-title"><?php the_title(); ?></p>
        <p class="staff-job-title"><?php the_field('staff-job-title'); ?></p>
    </a>
</div>
</div>

<?php endforeach;
wp_reset_postdata();?>

This is working using slug; ?> to display the class name however it is only displaying "veterinary-surgeons" on every single class name, when it should be displaying the relevant department on each item...

Hope that makes sense.

Many thanks.

</div>

To anyone who is interested I have now solved this using:

<?php $term_list = wp_get_post_terms($post->ID, 'department', array("fields" => "all")); ?>

and by using

<?php echo $term_list[0]->slug ;  ?>

as class name.

Thanks

</div>

You can solve this problem by this code also, Put this code inside while loop, 'portfolio_category' is custom taxonomy name

$terms = get_the_terms( $post->ID, 'portfolio_category' );  

                            if ( $terms && ! is_wp_error( $terms ) ) : 
                                 $links = array();
                                 foreach ( $terms as $term ) {
                                     $links[] = $term->name;
                                 }
                                 $tax_links = join( " ", str_replace(' ', '-', $links));          
                                 $tax = strtolower($tax_links);
                             else : 
                             $tax = '';                 
                             endif;