Validate this module's field data.
If there are validation problems, add to the $errors array (passed by reference). There is no return value.
$entity_type: The type of $entity.
$entity: The entity for the operation.
$field: The field structure for the operation.
$instance: The instance structure for $field on $entity's bundle.
$langcode: The language associated with $items.
$items: $entity->{$field['field_name']}[$langcode], or an empty array if unset.
$errors: The array of errors (keyed by field name, language code, and delta) that have already been reported for the entity. The function should add its errors to this array. Each error is an associative array with the following keys and values:
Note: this list is generated by pattern matching, so it may include some functions that are not actually implementations of this hook.
function hook_field_validate($entity_type, $entity, $field, $instance, $langcode, $items, &$errors) {
foreach ($items as $delta => $item) {
if (!empty($item['value'])) {
if (!empty($field['settings']['max_length']) && drupal_strlen($item['value']) > $field['settings']['max_length']) {
$errors[$field['field_name']][$langcode][$delta][] = array(
'error' => 'text_max_length',
'message' => t('%name: the value may not be longer than %max characters.', array(
'%name' => $instance['label'],
'%max' => $field['settings']['max_length'],
)),
);
}
}
}
}