Act on field_attach_validate().
This hook is invoked after the field module has performed the operation.
See field_attach_validate() for details and arguments.
$entity_type: The type of $entity; e.g., 'node' or 'user'.
$entity: The entity with fields to validate.
array $errors: The array of errors (keyed by field name, language code, and delta) that have already been reported for the entity. The function should add its errors to this array. Each error is an associative array with the following keys and values:
function hook_field_attach_validate($entity_type, $entity, &$errors) {
// Make sure any images in article nodes have an alt text.
if ($entity_type == 'node' && $entity->type == 'article' && !empty($entity->field_image)) {
foreach ($entity->field_image as $langcode => $items) {
foreach ($items as $delta => $item) {
if (!empty($item['fid']) && empty($item['alt'])) {
$errors['field_image'][$langcode][$delta][] = array(
'error' => 'field_example_invalid',
'message' => t('All images in articles need to have an alternative text set.'),
);
}
}
}
}
}