This should work for a custom taxonomy.
<?php
function get_related_posts() {
global $post;
$taxonomy = 'your_custom_taxonomy';
$terms = wp_get_post_terms( $post->ID, $taxonomy );
if($terms) {
$term_arr="";
foreach( $terms as $term ) {
$term_arr .= $term->slug . ','; // create array of term slugs
}
$args = array(
'showposts' => 5, // you can change this to whatever you need
'post__not_in' => array($post->ID) // exlude current post from results
'tax_query' => array(
array(
'taxonomy' => $taxonomy,
'field' => 'slug', // using 'slug' but can be either 'term_id', 'slug' or 'name'
'terms' => $term_arr // array of ID values, slugs or names depending what 'field' is set to
)
)
);
$related_posts = get_posts( $args );
if($related_posts) {
foreach ( $related_posts as $post ) : setup_postdata( $post );
// output whatever you want here
the_title(); // for example
endforeach;
} else {
echo 'No Related Posts';
}
}
wp_reset_postdata();
}
?>