Simple field to display static data
Ok, got this. As far as my field has nothing in $items, in order to print something I had to use this snippet:

function fblike_field_prepare_view($entity_type, $entities, $field, $instances, $langcode, &amp;$items) {
    foreach ($entities as $id =&gt; $entity) {
        if (empty($items[$id])) {
            $items[$id][0] = 'something';
        }
    }
}