WordPress Loop Error Using get_the_terms

If you get this WordPress Loop Error… “Warning: Invalid argument supplied for foreach() in [filepath].php on line [number]” when you try to loop over terms found using the WordPress function get_the_terms, you may find this information useful. It happens when you have a post that hasn’t been linked to any terms… but it caused by the lack of defensive code demonstrated below:

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

foreach($terms as $term) {
    echo $term->name ;
}

This code is a perfectly standard function call and loop that you’ll find in many themes, but it is missing an important check. The amended code, with the check added, is shown below.

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

if ($terms && !is_wp_error($terms)) {
    foreach($terms as $term) {
        echo $term->name ;
    }
}

By checking that we successfully obtained the terms before attempting to loop over them, we can now survive that errant post with missing taxonomical information.

By Steve Fenton on 1st February 2018 in