Preprocess a Field, Change Theming of a field

For thah you must use an additional process.

1. Create a custom module (Example : Here we use mymodule)

2. in the mymodule.module, add the hook hook_alter_element_info_alter and create a function '_mymodule_date_popup_process_alter'

Ex:

/**

 * implements hook_element_info_alter()

 *

 */

function mymodule_alter_element_info_alter(&$type) {

  if (isset($type['date_popup'])) {

    $type['date_popup']['#process'][] = '_mymodule_date_popup_process_alter';

  }

}

function _mymodule_date_popup_process_alter(&$element, &$form_state, $context) {

  unset($element['date']['#description']);

  if ($element['#name'] == 'node_changed') {

    $element['date']['#title'] = "The Date is";

  }

  return $element;

}