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Drupal example source code file (ajax.inc)

This example Drupal source code file (ajax.inc) is included in the DevDaily.com "Drupal Source Code Warehouse" project. The intent of this project is to help you "Learn Drupal by Example".

PHP - Drupal tags/keywords

array, command, commands, element, function, html, if, isset, php, return, selector, settings, type, variable

The ajax.inc Drupal example source code

<?php
// $Id: ajax.inc,v 1.42 2011/01/02 17:26:39 webchick Exp $

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

/**
 * @defgroup ajax AJAX framework
 * @{
 * Functions for Drupal's 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 property that includes #ajax['callback'] and
 *     omits #ajax['path']. See below about using #ajax['path'] to implement
 *     advanced use-cases that require something other than standard form
 *     handling.
 *   - On the specified element, AJAX processing is triggered by a change to
 *     that element.
 *   - The browser submits an HTTP POST request to the 'system/ajax' Drupal
 *     path.
 *   - The menu page callback for 'system/ajax', ajax_form_callback(), calls
 *     drupal_process_form() to process the form submission and rebuild the
 *     form if necessary. The form is processed in much the same way as if it
 *     were submitted without AJAX, with the same #process functions and
 *     validation and submission handlers called in either case, making it easy
 *     to create AJAX-enabled forms that degrade gracefully when JavaScript is
 *     disabled.
 *   - After form processing is complete, ajax_form_callback() calls the
 *     function named by #ajax['callback'], which returns the form element that
 *     has been updated and needs to be returned to the browser, or
 *     alternatively, an array of custom AJAX commands.
 *   - The page delivery callback for 'system/ajax', ajax_deliver(), renders the
 *     element returned by #ajax['callback'], and returns the JSON string
 *     created by ajax_render() to the browser.
 *   - The browser unserializes the returned JSON string into an array of
 *     command objects and executes each command, resulting in the old page
 *     content within and including the HTML element specified by
 *     #ajax['wrapper'] being replaced by the new content returned by
 *     #ajax['callback'], using a JavaScript animation effect specified by
 *     #ajax['effect'].
 *
 * 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 $form;
 * }
 *
 * function ajax_example_simplest_callback($form, $form_state) {
 *   // The form has already been submitted and updated. We can return the replaced
 *   // item as it is.
 *   return $form['replace_textfield'];
 * }
 * @endcode
 *
 * In the above example, the 'changethis' element is AJAX-enabled. The default
 * #ajax['event'] is 'change', so when the 'changethis' element changes,
 * an AJAX call is made. The form is submitted and reprocessed, and then the
 * callback is called.  In this case, the form has been automatically
 * built changing $form['replace_textfield']['#description'], so the callback
 * just returns that part of the form.
 *
 * To implement AJAX handling in a form, add '#ajax' to the form
 * definition of a field. That field will trigger an AJAX event when it is
 * clicked (or changed, depending on the kind of field). #ajax supports
 * the following parameters (either 'path' or 'callback' is required at least):
 * - #ajax['callback']: The callback to invoke to handle the server side of the
 *   AJAX event, which will receive a $form and $form_state as arguments, and
 *   returns a renderable array (most often a form or form fragment), an HTML
 *   string, or an array of AJAX commands. If returning a renderable array or
 *   a string, the value will replace the original element named in
 *   #ajax['wrapper'], and
 *   theme_status_messages()
 *   will be prepended to that
 *   element. (If the status messages are not wanted, return an array
 *   of AJAX commands instead.)
 *   #ajax['wrapper']. If an array of AJAX commands is returned, it will be
 *   executed by the calling code.
 * - #ajax['path']: The menu path to use for the request. This is often omitted
 *   and the default is used. This path should map
 *   to a menu page callback that returns data using ajax_render(). Defaults to
 *   'system/ajax', which invokes ajax_form_callback(), eventually calling
 *   the function named in #ajax['callback']. If you use a custom
 *   path, you must set up the menu entry and handle the entire callback in your
 *   own code.
 * - #ajax['wrapper']: The CSS ID of the area to be replaced by the content
 *   returned by the #ajax['callback'] function. The content returned from
 *   the callback will replace the entire element named by #ajax['wrapper'].
 *   The wrapper is usually created using #prefix and #suffix properties in the
 *   form. Note that this is the wrapper ID, not a CSS selector. So to replace
 *   the element referred to by the CSS selector #some-selector on the page,
 *   use #ajax['wrapper'] = 'some-selector', not '#some-selector'.
 * - #ajax['effect']: The jQuery effect to use when placing the new HTML.
 *   Defaults to no effect. Valid options are 'none', 'slide', or 'fade'.
 * - #ajax['speed']: The effect speed to use. Defaults to 'slow'. May be
 *   'slow', 'fast' or a number in milliseconds which represents the length
 *   of time the effect should run.
 * - #ajax['event']: The JavaScript event to respond to. This is normally
 *   selected automatically for the type of form widget being used, and
 *   is only needed if you need to override the default behavior.
 * - #ajax['method']: The jQuery method to use to place the new HTML.
 *   Defaults to 'replaceWith'. May be: 'replaceWith', 'append', 'prepend',
 *   'before', 'after', or 'html'. See the
 *   @link http://api.jquery.com/category/manipulation/ jQuery manipulators documentation @endlink
 *   for more information on these methods.
 * - #ajax['progress']: Choose either a throbber or progress bar that is
 *   displayed while awaiting a response from the callback, and add an optional
 *   message. Possible keys: 'type', 'message', 'url', 'interval'.
 *   More information is available in the
 *   @link http://api.drupal.org/api/drupal/developer--topics--forms_api_reference.html/7 Form API Reference @endlink
 *
 * In addition to using Form API for doing in-form modification, AJAX may be
 * enabled by adding classes to buttons and links. By adding the 'use-ajax'
 * class to a link, the link will be loaded via an AJAX call. When using this
 * method, the href of the link can contain '/nojs/' as part of the path. When
 * the AJAX framework makes the request, it will convert this to '/ajax/'.
 * The server is then able to easily tell if this request was made through an
 * actual AJAX request or in a degraded state, and respond appropriately.
 *
 * Similarly, submit buttons can be given the class 'use-ajax-submit'. The
 * form will then be submitted via AJAX to the path specified in the #action.
 * Like the ajax-submit class above, this path will have '/nojs/' replaced with
 * '/ajax/' so that the submit handler can tell if the form was submitted
 * in a degraded state or not.
 *
 * When responding to AJAX requests, the server should do what it needs to do
 * for that request, then create a commands array. This commands array will
 * be converted to a JSON object and returned to the client, which will then
 * iterate over the array and process it like a macro language.
 *
 * Each command item is an associative array which will be converted to a command
 * object on the JavaScript side. $command_item['command'] is the type of
 * command, e.g. 'alert' or 'replace', and will correspond to a method in the
 * Drupal.ajax[command] space. The command array may contain any other data
 * that the command needs to process, e.g. 'method', 'selector', 'settings', etc.
 *
 * Commands are usually created with a couple of helper functions, so they
 * look like this:
 * @code
 *   $commands = array();
 *   // Replace the content of '#object-1' on the page with 'some html here'.
 *   $commands[] = ajax_command_replace('#object-1', 'some html here');
 *   // Add a visual "changed" marker to the '#object-1' element.
 *   $commands[] = ajax_command_changed('#object-1');
 *   // Menu 'page callback' and #ajax['callback'] functions are supposed to
 *   // return render arrays. If returning an AJAX commands array, it must be
 *   // encapsulated in a render array structure.
 *   return array('#type' => 'ajax', '#commands' => $commands);
 * @endcode
 *
 * When returning an AJAX command array, it is often useful to have
 * status messages rendered along with other tasks in the command array.
 * In that case the the AJAX commands array may be constructed like this:
 * @code
 *   $commands = array();
 *   $commands[] = ajax_command_replace(NULL, $output);
 *   $commands[] = ajax_command_prepend(NULL, theme('status_messages'));
 *   return array('#type' => 'ajax', '#commands' => $commands);
 * @endcode
 *
 * See @link ajax_commands AJAX framework commands @endlink
 */

/**
 * Render a commands array into JSON.
 *
 * @param $commands
 *   A list of macro commands generated by the use of ajax_command_*()
 *   functions.
 */
function ajax_render($commands = array()) {
  // AJAX responses aren't rendered with html.tpl.php, so we have to call
  // drupal_get_css() and drupal_get_js() here, in order to have new files added
  // during this request to be loaded by the page. We only want to send back
  // files that the page hasn't already loaded, so we implement simple diffing
  // logic using array_diff_key().
  foreach (array('css', 'js') as $type) {
    // It is highly suspicious if $_POST['ajax_page_state'][$type] is empty,
    // since the base page ought to have at least one JS file and one CSS file
    // loaded. It probably indicates an error, and rather than making the page
    // reload all of the files, instead we return no new files.
    if (empty($_POST['ajax_page_state'][$type])) {
      $items[$type] = array();
    }
    else {
      $function = 'drupal_add_' . $type;
      $items[$type] = $function();
      drupal_alter($type, $items[$type]);
      // @todo Inline CSS and JS items are indexed numerically. These can't be
      //   reliably diffed with array_diff_key(), since the number can change
      //   due to factors unrelated to the inline content, so for now, we strip
      //   the inline items from AJAX responses, and can add support for them
      //   when drupal_add_css() and drupal_add_js() are changed to using md5()
      //   or some other hash of the inline content.
      foreach ($items[$type] as $key => $item) {
        if (is_numeric($key)) {
          unset($items[$type][$key]);
        }
      }
      // Ensure that the page doesn't reload what it already has.
      $items[$type] = array_diff_key($items[$type], $_POST['ajax_page_state'][$type]);
    }
  }

  // Settings are handled separately, later in this function, so that changes to
  // the ajaxPageState setting that occur during drupal_get_css() and
  // drupal_get_js() get included, and because the jQuery.extend() code produced
  // by drupal_get_js() for adding settings isn't appropriate during an AJAX
  // response, because it does not pass TRUE for the "deep" parameter, and
  // therefore, can clobber existing settings on the page.
  if (isset($items['js']['settings'])) {
    unset($items['js']['settings']);
  }

  // Render the HTML to load these files, and add AJAX commands to insert this
  // HTML in the page. We pass TRUE as the $skip_alter argument to prevent the
  // data from being altered again, as we already altered it above.
  $styles = drupal_get_css($items['css'], TRUE);
  $scripts_footer = drupal_get_js('footer', $items['js'], TRUE);
  $scripts_header = drupal_get_js('header', $items['js'], TRUE);

  $extra_commands = array();
  if (!empty($styles)) {
    $extra_commands[] = ajax_command_prepend('head', $styles);
  }
  if (!empty($scripts_header)) {
    $extra_commands[] = ajax_command_prepend('head', $scripts_header);
  }
  if (!empty($scripts_footer)) {
    $extra_commands[] = ajax_command_append('body', $scripts_footer);
  }
  if (!empty($extra_commands)) {
    $commands = array_merge($extra_commands, $commands);
  }

  $scripts = drupal_add_js();
  if (!empty($scripts['settings'])) {
    $settings = $scripts['settings'];
    // Automatically extract any settings added via drupal_add_js() and make
    // them the first command.
    array_unshift($commands, ajax_command_settings(call_user_func_array('array_merge_recursive', $settings['data']), TRUE));
  }

  // Allow modules to alter any AJAX response.
  drupal_alter('ajax_render', $commands);

  return drupal_json_encode($commands);
}

/**
 * Get a form submitted via #ajax during an AJAX callback.
 *
 * This will load a form from the form cache used during AJAX operations. It
 * pulls the form info from $_POST.
 *
 * @return
 *   An array containing the $form and $form_state. Use the list() function
 *   to break these apart:
 *   @code
 *     list($form, $form_state, $form_id, $form_build_id) = ajax_get_form();
 *   @endcode
 */
function ajax_get_form() {
  $form_state = form_state_defaults();

  $form_build_id = $_POST['form_build_id'];

  // Get the form from the cache.
  $form = form_get_cache($form_build_id, $form_state);
  if (!$form) {
    // If $form cannot be loaded from the cache, the form_build_id in $_POST
    // must be invalid, which means that someone performed a POST request onto
    // system/ajax without actually viewing the concerned form in the browser.
    // This is likely a hacking attempt as it never happens under normal
    // circumstances, so we just do nothing.
    watchdog('ajax', 'Invalid form POST data.', array(), WATCHDOG_WARNING);
    drupal_exit();
  }

  // Since some of the submit handlers are run, redirects need to be disabled.
  $form_state['no_redirect'] = TRUE;

  // When a form is rebuilt after AJAX processing, its #build_id and #action
  // should not change.
  // @see drupal_rebuild_form()
  $form_state['rebuild_info']['copy']['#build_id'] = TRUE;
  $form_state['rebuild_info']['copy']['#action'] = TRUE;

  // The form needs to be processed; prepare for that by setting a few internal
  // variables.
  $form_state['input'] = $_POST;
  $form_id = $form['#form_id'];

  return array($form, $form_state, $form_id, $form_build_id);
}

/**
 * Menu callback; handles AJAX requests for the #ajax Form API property.
 *
 * This rebuilds the form from cache and invokes the defined #ajax['callback']
 * to return an AJAX command structure for JavaScript. In case no 'callback' has
 * been defined, nothing will happen.
 *
 * The Form API #ajax property can be set both for buttons and other input
 * elements.
 *
 * This function is also the canonical example of how to implement
 * #ajax['path']. If processing is required that cannot be accomplished with
 * a callback, re-implement this function and set #ajax['path'] to the
 * enhanced function.
 */
function ajax_form_callback() {
  list($form, $form_state) = ajax_get_form();
  drupal_process_form($form['#form_id'], $form, $form_state);

  // We need to return the part of the form (or some other content) that needs
  // to be re-rendered so the browser can update the page with changed content.
  // Since this is the generic menu callback used by many AJAX elements, it is
  // up to the #ajax['callback'] function of the element (may or may not be a
  // button) that triggered the AJAX request to determine what needs to be
  // rendered.
  if (!empty($form_state['triggering_element'])) {
    $callback = $form_state['triggering_element']['#ajax']['callback'];
  }
  if (!empty($callback) && function_exists($callback)) {
    return $callback($form, $form_state);
  }
}

/**
 * Theme callback for AJAX requests.
 *
 * Many different pages can invoke an AJAX request to system/ajax or another
 * generic AJAX path. It is almost always desired for an AJAX response to be
 * rendered using the same theme as the base page, because most themes are built
 * with the assumption that they control the entire page, so if the CSS for two
 * themes are both loaded for a given page, they may conflict with each other.
 * For example, Bartik is Drupal's default theme, and Seven is Drupal's default
 * administration theme. Depending on whether the "Use the administration theme
 * when editing or creating content" checkbox is checked, the node edit form may
 * be displayed in either theme, but the AJAX response to the Field module's
 * "Add another item" button should be rendered using the same theme as the rest
 * of the page. Therefore, system_menu() sets the 'theme callback' for
 * 'system/ajax' to this function, and it is recommended that modules
 * implementing other generic AJAX paths do the same.
 */
function ajax_base_page_theme() {
  if (!empty($_POST['ajax_page_state']['theme']) && !empty($_POST['ajax_page_state']['theme_token'])) {
    $theme = $_POST['ajax_page_state']['theme'];
    $token = $_POST['ajax_page_state']['theme_token'];

    // Prevent a request forgery from giving a person access to a theme they
    // shouldn't be otherwise allowed to see. However, since everyone is allowed
    // to see the default theme, token validation isn't required for that, and
    // bypassing it allows most use-cases to work even when accessed from the
    // page cache.
    if ($theme === variable_get('theme_default', 'bartik') || drupal_valid_token($token, $theme)) {
      return $theme;
    }
  }
}

/**
 * Package and send the result of a page callback to the browser as an AJAX response.
 *
 * This function is the equivalent of drupal_deliver_html_page(), but for AJAX
 * requests. Like that function, it:
 * - Adds needed HTTP headers.
 * - Prints rendered output.
 * - Performs end-of-request tasks.
 *
 * @param $page_callback_result
 *   The result of a page callback. Can be one of:
 *   - NULL: to indicate no content.
 *   - An integer menu status constant: to indicate an error condition.
 *   - A string of HTML content.
 *   - A renderable array of content.
 *
 * @see drupal_deliver_html_page()
 */
function ajax_deliver($page_callback_result) {
  // Emit a Content-Type HTTP header if none has been added by the page callback
  // or by a wrapping delivery callback.
  if (is_null(drupal_get_http_header('Content-Type'))) {
    // The standard header for JSON is application/json.
    // @see http://www.ietf.org/rfc/rfc4627.txt?number=4627
    // However, browsers do not allow JavaScript to read the contents of a
    // user's local files. To work around that, jQuery submits forms containing
    // a file input element to an IFRAME, instead of using XHR.
    // @see http://malsup.com/jquery/form/#file-upload
    // When Internet Explorer receives application/json content in an IFRAME, it
    // treats it as a file download and prompts the user to save it. To prevent
    // that, we return the content as text/plain. But only for POST requests,
    // since jQuery should always use XHR for GET requests and the incorrect
    // mime type should not end up in page or proxy server caches.
    // @see http://drupal.org/node/995854
    $iframe_upload = !isset($_SERVER['HTTP_X_REQUESTED_WITH']) || $_SERVER['HTTP_X_REQUESTED_WITH'] != 'XMLHttpRequest';
    if ($iframe_upload && $_SERVER['REQUEST_METHOD'] == 'POST') {
      drupal_add_http_header('Content-Type', 'text/plain; charset=utf-8');
    }
    else {
      drupal_add_http_header('Content-Type', 'application/json; charset=utf-8');
    }
  }

  // Normalize whatever was returned by the page callback to an AJAX commands
  // array.
  $commands = array();
  if (!isset($page_callback_result)) {
    // Simply delivering an empty commands array is sufficient. This results
    // in the AJAX request being completed, but nothing being done to the page.
  }
  elseif (is_int($page_callback_result)) {
    switch ($page_callback_result) {
      case MENU_NOT_FOUND:
        $commands[] = ajax_command_alert(t('The requested page could not be found.'));
        break;

      case MENU_ACCESS_DENIED:
        $commands[] = ajax_command_alert(t('You are not authorized to access this page.'));
        break;

      case MENU_SITE_OFFLINE:
        $commands[] = ajax_command_alert(filter_xss_admin(variable_get('maintenance_mode_message',
          t('@site is currently under maintenance. We should be back shortly. Thank you for your patience.', array('@site' => variable_get('site_name', 'Drupal'))))));
        break;
    }
  }
  elseif (is_array($page_callback_result) && isset($page_callback_result['#type']) && ($page_callback_result['#type'] == 'ajax')) {
    // Complex AJAX callbacks can return a result that contains an error message
    // or a specific set of commands to send to the browser.
    $page_callback_result += element_info('ajax');
    $error = $page_callback_result['#error'];
    if (isset($error) && $error !== FALSE) {
      if ((empty($error) || $error === TRUE)) {
        $error = t('An error occurred while handling the request: The server received invalid input.');
      }
      $commands[] = ajax_command_alert($error);
    }
    else {
      $commands = $page_callback_result['#commands'];
    }
  }
  else {
    // Like normal page callbacks, simple AJAX callbacks can return HTML
    // content, as a string or render array. This HTML is inserted in some
    // relationship to #ajax['wrapper'], as determined by which jQuery DOM
    // manipulation method is used. The method used is specified by
    // #ajax['method']. The default method is 'replaceWith', which completely
    // replaces the old wrapper element and its content with the new HTML.
    $html = is_string($page_callback_result) ? $page_callback_result : drupal_render($page_callback_result);
    $commands[] = ajax_command_insert(NULL, $html);
    // Add the status messages inside the new content's wrapper element, so that
    // on subsequent AJAX requests, it is treated as old content.
    $commands[] = ajax_command_prepend(NULL, theme('status_messages'));
  }

  // Unlike the recommendation in http://malsup.com/jquery/form/#file-upload,
  // we do not have to wrap the JSON string in a TEXTAREA, because
  // drupal_json_encode() returns an HTML-safe JSON string.
  print ajax_render($commands);
  ajax_footer();
}

/**
 * Perform end-of-AJAX-request tasks.
 *
 * This function is the equivalent of drupal_page_footer(), but for AJAX
 * requests.
 *
 * @see drupal_page_footer()
 */
function ajax_footer() {
  // Even for AJAX requests, invoke hook_exit() implementations. There may be
  // modules that need very fast AJAX responses, and therefore, run AJAX
  // requests with an early bootstrap.
  if (drupal_get_bootstrap_phase() == DRUPAL_BOOTSTRAP_FULL && (!defined('MAINTENANCE_MODE') || MAINTENANCE_MODE != 'update')) {
    module_invoke_all('exit');
  }

  // Commit the user session. See above comment about the possibility of this
  // function running without session.inc loaded.
  if (function_exists('drupal_session_commit')) {
    drupal_session_commit();
  }
}

/**
 * Form element process callback to handle #ajax.
 *
 * @param $element
 *   An associative array containing the properties of the element.
 *
 * @return
 *   The processed element.
 *
 * @see ajax_pre_render_element()
 */
function ajax_process_form($element, &$form_state) {
  $element = ajax_pre_render_element($element);
  if (!empty($element['#ajax_processed'])) {
    $form_state['cache'] = TRUE;
  }
  return $element;
}

/**
 * Add AJAX information about an element to the page to communicate with JavaScript.
 *
 * If #ajax['path'] is set on an element, this additional JavaScript is added
 * to the page header to attach the AJAX behaviors. See ajax.js for more
 * information.
 *
 * @param $element
 *   An associative array containing the properties of the element.
 *   Properties used:
 *   - #ajax['event']
 *   - #ajax['path']
 *   - #ajax['options']
 *   - #ajax['wrapper']
 *   - #ajax['parameters']
 *   - #ajax['effect']
 *
 * @return
 *   The processed element with the necessary JavaScript attached to it.
 */
function ajax_pre_render_element($element) {
  // Skip already processed elements.
  if (isset($element['#ajax_processed'])) {
    return $element;
  }
  // Initialize #ajax_processed, so we do not process this element again.
  $element['#ajax_processed'] = FALSE;

  // Nothing to do if there is neither a callback nor a path.
  if (!(isset($element['#ajax']['callback']) || isset($element['#ajax']['path']))) {
    return $element;
  }

  // Add a reasonable default event handler if none was specified.
  if (isset($element['#ajax']) && !isset($element['#ajax']['event'])) {
    switch ($element['#type']) {
      case 'submit':
      case 'button':
      case 'image_button':
        // Use the mousedown instead of the click event because form
        // submission via pressing the enter key triggers a click event on
        // submit inputs, inappropriately triggering AJAX behaviors.
        $element['#ajax']['event'] = 'mousedown';
        // Attach an additional event handler so that AJAX behaviors
        // can be triggered still via keyboard input.
        $element['#ajax']['keypress'] = TRUE;
        break;

      case 'password':
      case 'textfield':
      case 'textarea':
        $element['#ajax']['event'] = 'blur';
        break;

      case 'radio':
      case 'checkbox':
      case 'select':
        $element['#ajax']['event'] = 'change';
        break;

      case 'link':
        $element['#ajax']['event'] = 'click';
        break;

      default:
        return $element;
    }
  }

  // Attach JavaScript settings to the element.
  if (isset($element['#ajax']['event'])) {
    $element['#attached']['library'][] = array('system', 'jquery.form');
    $element['#attached']['library'][] = array('system', 'drupal.ajax');

    $settings = $element['#ajax'];

    // Assign default settings.
    $settings += array(
      'path' => 'system/ajax',
      'options' => array(),
    );

    // @todo Legacy support. Remove in Drupal 8.
    if (isset($settings['method']) && $settings['method'] == 'replace') {
      $settings['method'] = 'replaceWith';
    }

    // Change path to URL.
    $settings['url'] = url($settings['path'], $settings['options']);
    unset($settings['path'], $settings['options']);

    // Add special data to $settings['submit'] so that when this element
    // triggers an AJAX submission, Drupal's form processing can determine which
    // element triggered it.
    // @see _form_element_triggered_scripted_submission()
    if (isset($settings['trigger_as'])) {
      // An element can add a 'trigger_as' key within #ajax to make the element
      // submit as though another one (for example, a non-button can use this
      // to submit the form as though a button were clicked). When using this,
      // the 'name' key is always required to identify the element to trigger
      // as. The 'value' key is optional, and only needed when multiple elements
      // share the same name, which is commonly the case for buttons.
      $settings['submit']['_triggering_element_name'] = $settings['trigger_as']['name'];
      if (isset($settings['trigger_as']['value'])) {
        $settings['submit']['_triggering_element_value'] = $settings['trigger_as']['value'];
      }
      unset($settings['trigger_as']);
    }
    elseif (isset($element['#name'])) {
      // Most of the time, elements can submit as themselves, in which case the
      // 'trigger_as' key isn't needed, and the element's name is used.
      $settings['submit']['_triggering_element_name'] = $element['#name'];
      // If the element is a (non-image) button, its name may not identify it
      // uniquely, in which case a match on value is also needed.
      // @see _form_button_was_clicked()
      if (isset($element['#button_type']) && empty($element['#has_garbage_value'])) {
        $settings['submit']['_triggering_element_value'] = $element['#value'];
      }
    }

    // Convert a simple #ajax['progress'] string into an array.
    if (isset($settings['progress']) && is_string($settings['progress'])) {
      $settings['progress'] = array('type' => $settings['progress']);
    }
    // Change progress path to a full URL.
    if (isset($settings['progress']['path'])) {
      $settings['progress']['url'] = url($settings['progress']['path']);
      unset($settings['progress']['path']);
    }

    $element['#attached']['js'][] = array(
      'type' => 'setting',
      'data' => array('ajax' => array($element['#id'] => $settings)),
    );

    // Indicate that AJAX processing was successful.
    $element['#ajax_processed'] = TRUE;
  }
  return $element;
}

/**
 * @} End of "defgroup ajax".
 */

/**
 * @defgroup ajax_commands AJAX framework commands
 * @{
 * Functions to create various AJAX commands.
 *
 * These functions can be used to create arrays for use with the
 * ajax_render() function.
 */

/**
 * Creates a Drupal AJAX 'alert' command.
 *
 * The 'alert' command instructs the client to display a JavaScript alert
 * dialog box.
 *
 * This command is implemented by Drupal.ajax.prototype.commands.alert()
 * defined in misc/ajax.js.
 *
 * @param $text
 *   The message string to display to the user.
 *
 * @return
 *   An array suitable for use with the ajax_render() function.
 */
function ajax_command_alert($text) {
  return array(
    'command' => 'alert',
    'text' => $text,
  );
}

/**
 * Creates a Drupal AJAX 'insert' command using the method in #ajax['method'].
 *
 * This command instructs the client to insert the given HTML using whichever
 * jQuery DOM manipulation method has been specified in the #ajax['method']
 * variable of the element that triggered the request.
 *
 * This command is implemented by Drupal.ajax.prototype.commands.insert()
 * defined in misc/ajax.js.
 *
 * @param $selector
 *   A jQuery selector string. If the command is a response to a request from
 *   an #ajax form element then this value can be NULL.
 * @param $html
 *   The data to use with the jQuery method.
 * @param $settings
 *   An optional array of settings that will be used for this command only.
 *
 * @return
 *   An array suitable for use with the ajax_render() function.
 */
function ajax_command_insert($selector, $html, $settings = NULL) {
  return array(
    'command' => 'insert',
    'method' => NULL,
    'selector' => $selector,
    'data' => $html,
    'settings' => $settings,
  );
}

/**
 * Creates a Drupal AJAX 'insert/replaceWith' command.
 *
 * The 'insert/replaceWith' command instructs the client to use jQuery's
 * replaceWith() method to replace each element matched matched by the given
 * selector with the given HTML.
 *
 * This command is implemented by Drupal.ajax.prototype.commands.insert()
 * defined in misc/ajax.js.
 *
 * @param $selector
 *   A jQuery selector string. If the command is a response to a request from
 *   an #ajax form element then this value can be NULL.
 * @param $html
 *   The data to use with the jQuery replaceWith() method.
 * @param $settings
 *   An optional array of settings that will be used for this command only.
 *
 * @return
 *   An array suitable for use with the ajax_render() function.
 *
 * See @link http://docs.jquery.com/Manipulation/replaceWith#content jQuery replaceWith command @endlink
 */
function ajax_command_replace($selector, $html, $settings = NULL) {
  return array(
    'command' => 'insert',
    'method' => 'replaceWith',
    'selector' => $selector,
    'data' => $html,
    'settings' => $settings,
  );
}

/**
 * Creates a Drupal AJAX 'insert/html' command.
 *
 * The 'insert/html' command instructs the client to use jQuery's html()
 * method to set the HTML content of each element matched by the given
 * selector while leaving the outer tags intact.
 *
 * This command is implemented by Drupal.ajax.prototype.commands.insert()
 * defined in misc/ajax.js.
 *
 * @param $selector
 *   A jQuery selector string. If the command is a response to a request from
 *   an #ajax form element then this value can be NULL.
 * @param $html
 *   The data to use with the jQuery html() method.
 * @param $settings
 *   An optional array of settings that will be used for this command only.
 *
 * @return
 *   An array suitable for use with the ajax_render() function.
 *
 * @see http://docs.jquery.com/Attributes/html#val
 */
function ajax_command_html($selector, $html, $settings = NULL) {
  return array(
    'command' => 'insert',
    'method' => 'html',
    'selector' => $selector,
    'data' => $html,
    'settings' => $settings,
  );
}

/**
 * Creates a Drupal AJAX 'insert/prepend' command.
 *
 * The 'insert/prepend' command instructs the client to use jQuery's prepend()
 * method to prepend the given HTML content to the inside each element matched
 * by the given selector.
 *
 * This command is implemented by Drupal.ajax.prototype.commands.insert()
 * defined in misc/ajax.js.
 *
 * @param $selector
 *   A jQuery selector string. If the command is a response to a request from
 *   an #ajax form element then this value can be NULL.
 * @param $html
 *   The data to use with the jQuery prepend() method.
 * @param $settings
 *   An optional array of settings that will be used for this command only.
 *
 * @return
 *   An array suitable for use with the ajax_render() function.
 *
 * @see http://docs.jquery.com/Manipulation/prepend#content
 */
function ajax_command_prepend($selector, $html, $settings = NULL) {
  return array(
    'command' => 'insert',
    'method' => 'prepend',
    'selector' => $selector,
    'data' => $html,
    'settings' => $settings,
  );
}

/**
 * Creates a Drupal AJAX 'insert/append' command.
 *
 * The 'insert/append' command instructs the client to use jQuery's append()
 * method to append the given HTML content to the inside each element matched
 * by the given selector.
 *
 * This command is implemented by Drupal.ajax.prototype.commands.insert()
 * defined in misc/ajax.js.
 *
 * @param $selector
 *   A jQuery selector string. If the command is a response to a request from
 *   an #ajax form element then this value can be NULL.
 * @param $html
 *   The data to use with the jQuery append() method.
 * @param $settings
 *   An optional array of settings that will be used for this command only.
 *
 * @return
 *   An array suitable for use with the ajax_render() function.
 *
 * @see http://docs.jquery.com/Manipulation/append#content
 */
function ajax_command_append($selector, $html, $settings = NULL) {
  return array(
    'command' => 'insert',
    'method' => 'append',
    'selector' => $selector,
    'data' => $html,
    'settings' => $settings,
  );
}

/**
 * Creates a Drupal AJAX 'insert/after' command.
 *
 * The 'insert/after' command instructs the client to use jQuery's after()
 * method to insert the given HTML content after each element matched by
 * the given selector.
 *
 * This command is implemented by Drupal.ajax.prototype.commands.insert()
 * defined in misc/ajax.js.
 *
 * @param $selector
 *   A jQuery selector string. If the command is a response to a request from
 *   an #ajax form element then this value can be NULL.
 * @param $html
 *   The data to use with the jQuery after() method.
 * @param $settings
 *   An optional array of settings that will be used for this command only.
 *
 * @return
 *   An array suitable for use with the ajax_render() function.
 *
 * @see http://docs.jquery.com/Manipulation/after#content
 */
function ajax_command_after($selector, $html, $settings = NULL) {
  return array(
    'command' => 'insert',
    'method' => 'after',
    'selector' => $selector,
    'data' => $html,
    'settings' => $settings,
  );
}

/**
 * Creates a Drupal AJAX 'insert/before' command.
 *
 * The 'insert/before' command instructs the client to use jQuery's before()
 * method to insert the given HTML content before each of elements matched by
 * the given selector.
 *
 * This command is implemented by Drupal.ajax.prototype.commands.insert()
 * defined in misc/ajax.js.
 *
 * @param $selector
 *   A jQuery selector string. If the command is a response to a request from
 *   an #ajax form element then this value can be NULL.
 * @param $html
 *   The data to use with the jQuery before() method.
 * @param $settings
 *   An optional array of settings that will be used for this command only.
 *
 * @return
 *   An array suitable for use with the ajax_render() function.
 *
 * @see http://docs.jquery.com/Manipulation/before#content
 */
function ajax_command_before($selector, $html, $settings = NULL) {
  return array(
    'command' => 'insert',
    'method' => 'before',
    'selector' => $selector,
    'data' => $html,
    'settings' => $settings,
  );
}

/**
 * Creates a Drupal AJAX 'remove' command.
 *
 * The 'remove' command instructs the client to use jQuery's remove() method
 * to remove each of elements matched by the given selector, and everything
 * within them.
 *
 * This command is implemented by Drupal.ajax.prototype.commands.remove()
 * defined in misc/ajax.js.
 *
 * @param $selector
 *   A jQuery selector string. If the command is a response to a request from
 *   an #ajax form element then this value can be NULL.
 *
 * @return
 *   An array suitable for use with the ajax_render() function.
 *
 * @see http://docs.jquery.com/Manipulation/remove#expr
 */
function ajax_command_remove($selector) {
  return array(
    'command' => 'remove',
    'selector' => $selector,
  );
}

/**
 * Creates a Drupal AJAX 'changed' command.
 *
 * This command instructs the client to mark each of the elements matched by the
 * given selector as 'ajax-changed'.
 *
 * This command is implemented by Drupal.ajax.prototype.commands.changed()
 * defined in misc/ajax.js.
 *
 * @param $selector
 *   A jQuery selector string. If the command is a response to a request from
 *   an #ajax form element then this value can be NULL.
 * @param $asterisk
 *   An optional CSS selector which must be inside $selector. If specified,
 *   an asterisk will be appended to the HTML inside the $asterisk selector.
 *
 * @return
 *   An array suitable for use with the ajax_render() function.
 */
function ajax_command_changed($selector, $asterisk = '') {
  return array(
    'command' => 'changed',
    'selector' => $selector,
    'asterisk' => $asterisk,
  );
}

/**
 * Creates a Drupal AJAX 'css' command.
 *
 * The 'css' command will instruct the client to use the jQuery css() method
 * to apply the CSS arguments to elements matched by the given selector.
 *
 * This command is implemented by Drupal.ajax.prototype.commands.css()
 * defined in misc/ajax.js.
 *
 * @param $selector
 *   A jQuery selector string. If the command is a response to a request from
 *   an #ajax form element then this value can be NULL.
 * @param $argument
 *   An array of key/value pairs to set in the CSS for the selector.
 *
 * @return
 *   An array suitable for use with the ajax_render() function.
 *
 * @see http://docs.jquery.com/CSS/css#properties
 */
function ajax_command_css($selector, $argument) {
  return array(
    'command' => 'css',
    'selector' => $selector,
    'argument' => $argument,
  );
}

/**
 * Creates a Drupal AJAX 'settings' command.
 *
 * The 'settings' command instructs the client either to use the given array as
 * the settings for ajax-loaded content or to extend Drupal.settings with the
 * given array, depending on the value of the $merge parameter.
 *
 * This command is implemented by Drupal.ajax.prototype.commands.settings()
 * defined in misc/ajax.js.
 *
 * @param $argument
 *   An array of key/value pairs to add to the settings. This will be utilized
 *   for all commands after this if they do not include their own settings
 *   array.
 * @param $merge
 *   Whether or not the passed settings in $argument should be merged into the
 *   global Drupal.settings on the page. By default (FALSE), the settings that
 *   are passed to Drupal.attachBehaviors will not include the global
 *   Drupal.settings.
 *
 * @return
 *   An array suitable for use with the ajax_render() function.
 */
function ajax_command_settings($argument, $merge = FALSE) {
  return array(
    'command' => 'settings',
    'settings' => $argument,
    'merge' => $merge,
  );
}

/**
 * Creates a Drupal AJAX 'data' command.
 *
 * The 'data' command instructs the client to attach the name=value pair of
 * data to the selector via jQuery's data cache.
 *
 * This command is implemented by Drupal.ajax.prototype.commands.data()
 * defined in misc/ajax.js.
 *
 * @param $selector
 *   A jQuery selector string. If the command is a response to a request from
 *   an #ajax form element then this value can be NULL.
 * @param $name
 *   The name or key (in the key value pair) of the data attached to this
 *   selector.
 * @param $value
 *   The value of the data. Not just limited to strings can be any format.
 *
 * @return
 *   An array suitable for use with the ajax_render() function.
 *
 * @see http://docs.jquery.com/Core/data#namevalue
 */
function ajax_command_data($selector, $name, $value) {
  return array(
    'command' => 'data',
    'selector' => $selector,
    'name' => $name,
    'value' => $value,
  );
}

/**
 * Creates a Drupal AJAX 'invoke' command.
 *
 * The 'invoke' command will instruct the client to invoke the given jQuery
 * method with the supplied arguments on the elements matched by the given
 * selector. Intended for simple jQuery commands, such as attr(), addClass(),
 * removeClass(), toggleClass(), etc.
 *
 * This command is implemented by Drupal.ajax.prototype.commands.invoke()
 * defined in misc/ajax.js.
 *
 * @param $selector
 *   A jQuery selector string. If the command is a response to a request from
 *   an #ajax form element then this value can be NULL.
 * @param $method
 *   The jQuery method to invoke.
 * @param $arguments
 *   (optional) A list of arguments to the jQuery $method, if any.
 *
 * @return
 *   An array suitable for use with the ajax_render() function.
 */
function ajax_command_invoke($selector, $method, array $arguments = array()) {
  return array(
    'command' => 'invoke',
    'selector' => $selector,
    'method' => $method,
    'arguments' => $arguments,
  );
}

/**
 * Creates a Drupal AJAX 'restripe' command.
 *
 * The 'restripe' command instructs the client to restripe a table. This is
 * usually used after a table has been modified by a replace or append command.
 *
 * This command is implemented by Drupal.ajax.prototype.commands.restripe()
 * defined in misc/ajax.js.
 *
 * @param $selector
 *   A jQuery selector string.
 *
 * @return
 *   An array suitable for use with the ajax_render() function.
 */
function ajax_command_restripe($selector) {
  return array(
    'command' => 'restripe',
    'selector' => $selector,
  );
}

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