function ajax_deliver

Packages and sends the result of a page callback as an Ajax response.

This function is the equivalent of backdrop_deliver_html_page(), but for Ajax requests. Like that function, it:

• Adds needed HTTP headers.
• Prints rendered output.
• Performs end-of-request tasks.

Parameters

$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 also

backdrop_deliver_html_page()

Related topics

File

includes/ajax.inc, line 477

Functions for use with Backdrop's Ajax framework.

Code

function ajax_deliver($page_callback_result) {
  // Browsers do not allow JavaScript to read the contents of a user's local
  // files. To work around that, the jQuery Form plugin submits forms containing
  // a file input element to an IFRAME, instead of using XHR. Browsers do not
  // normally expect JSON strings as content within an IFRAME, so the response
  // must be customized accordingly.
  // @see http://malsup.com/jquery/form/#file-upload
  // @see Backdrop.ajax.prototype.beforeSend()
  $iframe_upload = !empty($_POST['ajax_iframe_upload']);

  // Emit a Content-Type HTTP header if none has been added by the page callback
  // or by a wrapping delivery callback.
  if (is_null(backdrop_get_http_header('Content-Type'))) {
    if (!$iframe_upload) {
      // Standard JSON can be returned to a browser's XHR object, and to
      // non-browser user agents.
      // @see http://www.ietf.org/rfc/rfc4627.txt?number=4627
      backdrop_add_http_header('Content-Type', 'application/json; charset=utf-8');
    }
    else {
      // Browser IFRAMEs expect HTML. With most other content types, Internet
      // Explorer presents the user with a download prompt.
      backdrop_add_http_header('Content-Type', 'text/html; charset=utf-8');
    }
  }

  // Let ajax.js know that this response is safe to process.
  ajax_set_verification_header();

  // Print the response.
  $commands = ajax_prepare_response($page_callback_result);
  $json = ajax_render($commands);
  if (!$iframe_upload) {
    // Standard JSON can be returned to a browser's XHR object, and to
    // non-browser user agents.
    print $json;
  }
  else {
    // Browser IFRAMEs expect HTML. Browser extensions, such as Linkification
    // and Skype's Browser Highlighter, convert URLs, phone numbers, etc. into
    // links. This corrupts the JSON response. Protect the integrity of the
    // JSON data by making it the value of a textarea.
    // @see http://malsup.com/jquery/form/#file-upload
    // @see http://drupal.org/node/1009382
    print '<textarea>' . $json . '</textarea>';
  }

  // Perform end-of-request tasks.
  ajax_footer();
}