function ajax_render

Renders a commands array into JSON.

Parameters

$commands: A list of macro commands generated by the use of ajax_command_*() functions.

Return value

string: A JSON string of the AJAX commands.

Related topics

File

core/includes/ajax.inc, line 230

Functions for use with Backdrop's Ajax framework.

Code

function ajax_render($commands = array()) {
  // Although ajax_deliver() does this, some contributed and custom modules
  // render Ajax responses without using that delivery callback.
  ajax_set_verification_header();

  // Ajax responses aren't rendered with html.tpl.php, so we have to call
  // backdrop_get_css() and backdrop_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 = 'backdrop_add_' . $type;
      $items[$type] = $function();
      backdrop_alter($type, $items[$type]);
      // @todo Inline CSS and JS items are indexed numerically. These can't be
      //   reliably differed 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 backdrop_add_css() and backdrop_add_js() are changed to use a
      //   hash of the inline content as the array key.
      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]);
    }
  }

  // Render the HTML to load these files, and add AJAX commands to insert this
  // HTML in the page. We pass TRUE as the $skip_alter argument to prevent the
  // data from being altered again, as we already altered it above. Settings are
  // handled separately, afterwards.
  if (isset($items['js']['settings'])) {
    unset($items['js']['settings']);
  }
  $styles = backdrop_get_css($items['css'], TRUE);
  $scripts_footer = backdrop_get_js('footer', $items['js'], TRUE);
  $scripts_header = backdrop_get_js('header', $items['js'], TRUE);

  $extra_commands = array();
  if (!empty($styles)) {
    $extra_commands[] = ajax_command_add_css($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);
  }

  // Now add a command to merge changes and additions to Backdrop.settings.
  $scripts = backdrop_add_js();
  backdrop_alter('js', $scripts);
  if (!empty($scripts['settings'])) {
    $settings = $scripts['settings'];
    array_unshift($commands, ajax_command_settings(backdrop_array_merge_deep_array($settings['data']), TRUE));
  }

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

  return backdrop_json_encode($commands);
}