• John Huebner

• September 24, 2018 at 10:08 pm

Let’s say that your field name is “text_field” and it has a field key of “field_123456”
Notice I’m only using the field key, since you must use the field key for the new values you might just as well use it for both.

add_filter('acf/save_post', 'my_compare_acf_fields', 1);
function my_compare_acf_fields($post_id) {
  $old_value = get_field('field_123456', $post_id);
  $new_value = '';
  if (isset($_POST['acf']['field_123456'])) {
    $new_value = $_POST['acf']['field_123456'];
  }
  if ($new_value != $old_value) {
    // value has changed, do something
  }
}