Conditional display for custom fields/taxonomy

Question

If there's a value for the custom field, I want it to display the value. If there's no value for the custom field, I want it to display "N/A". I have this working for custom fields but cant replicate the same functionality for a custom taxonomy.

This works for a custom field:

$url = get_post_meta( get_the_ID(), 'event-code', true );
if ( ! empty( $url ) ) {
print ( $url );
}
else {
print 'N/A';
}

In the case of a custom taxonomy entry with a value, this displays both the value and "N/A":

$promtax = the_terms( get_the_ID(), 'promotion','' );
if ( ! empty( $promtax ) ) {
print ( $promtax );
}
else {
print 'N/A';
}

I've used variations and combinations of isset, empty without any luck. Thanks.

Answer 1

the_terms() echoes output. To assign output to a variable and check if there is any you need to use get_the_term_list() instead.

Note that it might also return WP_Error object (which won't be empty) so you will need to check for it as well with is_wp_error().

Answer 2

Use get_the_terms. It will either return an empty array, a WP_Error object, or the terms. So you can check it they exist.

<?php
$terms = get_the_terms( $post->ID, 'promotion' );
if( $terms && ! is_wp_error( $terms ) )
{
    foreach( $terms as $term )
    {
        // each $term is an object. you could do something like this....
        $link = get_term_link( $term );
        echo '<a href="' . esc_url( $link ) . '">' . esc_attr( $term->name ) . '</a>, ';            
    }
}
else
{
    // no terms found
    echo 'N/A'; 
}

get_the_term_list would work the same way, but you'll get less control of the output.

<?php
$terms = get_the_term_list( $post->ID, 'promotion', 'Promotions: ', ' ', '' );
if( $terms && ! is_wp_error( $terms ) )
{
    // terms found!
    echo $terms;    
}
else
{
    // no terms found
    echo 'n/a';
}