Get first term by post id

With the following function you can get the first term of a post by the post’s id. The function requires 3 parameters:

$post_id
The id of the post to retrieve the term from.

$taxonomy
The taxonomy to retrieve terms from.

$output
What you want to return from the term. (term_id, name, slug, description etc.).

// Get first term by post id
function get_first_term_by_id( $post_id, $taxonomy, $output = 'term_id' ) {
   if ( isset( $post_id ) && isset( $taxonomy ) ) {
      $terms = get_the_terms( $post_id, $taxonomy );
      if ( ! empty( $terms ) ){
         $term = array_shift( $terms );
      }
      return $term->$output;
   }
}