ajax.inc

<?php
// $Id: ajax.inc,v 1.31 2010/04/30 08:07:54 dries Exp $

/**
 * @file
 * Functions for use with Drupal's AJAX framework.
 */

/**
 * @defgroup ajax AJAX framework
 * @{
 * Drupal's AJAX framework is used to dynamically update parts of a page's HTML
 * based on data from the server. Upon a specified event, such as a button
 * click, a callback function is triggered which performs server-side logic and
 * may return updated markup, which is then replaced on-the-fly with no page
 * refresh necessary.
 *
 * This framework creates a PHP macro language that allows the server to
 * instruct JavaScript to perform actions on the client browser. When using
 * forms, it can be used with the #ajax property.
 * The #ajax property can be used to bind events to the AJAX framework. By
 * default, #ajax uses 'system/ajax' as its path for submission and thus calls
 * ajax_form_callback() and a defined #ajax['callback'] function.
 * However, you may optionally specify a different path to request or a
 * different callback function to invoke, which can return updated HTML or can
 * also return a richer set of @link ajax_commands AJAX framework commands @endlink.
 *
 * Standard form handling is as follows:
 *   - A form element has a #ajax member.
 *   - On the specified element, AJAX processing is triggered by a change to
 *     that element.
 *   - The form is submitted and rebuilt.
 *   - The function named by #ajax['callback'] is called, which returns content
 *     or an array of AJAX framework commands.
 *   - The content returned by the callback replaces the div on the page
 *     referenced by #ajax['wrapper'].
 *
 * A simple example of basic AJAX use from the
 * @link http://drupal.org/project/examples Examples module @endlink follows:
 * @code
 * function main_page() {
 *   return drupal_get_form('ajax_example_simplest');
 * }
 *
 * function ajax_example_simplest($form, &$form_state) {
 *   $form = array();
 *   $form['changethis'] = array(
 *     '#type' => 'select',
 *     '#options' => array(
 *       'one' => 'one',
 *       'two' => 'two',
 *       'three' => 'three',
 *     ),
 *     '#ajax' => array(
 *       'callback' => 'ajax_example_simplest_callback',
 *       'wrapper' => 'replace_textfield_div',
 *      ),
 *   );

 *   // This entire form element will be replaced with an updated value.
 *   $form['replace_textfield'] = array(
 *     '#type' => 'textfield',
 *     '#title' => t("The default value will be changed"),
 *     '#description' => t("Say something about why you chose") . "'" .
 *       (!empty($form_state['values']['changethis'])
 *       ? $form_state['values']['changethis'] : t("Not changed yet")) . "'",
 *     '#prefix' => '<div id="replace_textfield_div">',
 *     '#suffix' => '</div>',
 *   );
 *   return $form;