I am trying to code Drupal Ajax forms in Drupal pages (Drupal Content type: Basic page). However, it seems like the callback does not work, because when I remove the callback function nothing changes, and when I paste it back nothing changes.

Here is my code:

$the_ajax3_form = drupal_get_form('ajax_example_simplestt');
print drupal_render($the_ajax3_form);

function ajax_example_simplestt($form, &$form_state) {
  $form = array();
  $form['changethis'] = array(
    '#title' => t("Choose something and explain why"),
    '#type' => 'select',
    '#options' => array(
      'one' => 'one',
      'two' => 'two',
      'three' => 'three',
    '#ajax' => array(
      'callback' => 'ajax_example_simplestt_callback',
      'wrapper' => 'replace_textfield_div',

  $form['replace_textfield'] = array(
    '#type' => 'textfield',
    '#prefix' => '<div id="replace_textfield_div">',
    '#suffix' => '</div>',

  if (!empty($form_state['values']['changethis'])) {
    $form['replace_textfield']['#description'] = t("Say why you chose '@value'", array('@value' => $form_state['values']['changethis']));
  return $form;

function ajax_example_simplestt_callback($form, $form_state) {
  return $form['replace_textfield'];

Your AJAX function callback is misspelled. This would be why it is not getting called.

Change ajax_example_simplest_callback to ajax_example_simplestt_callback.

Whichever spelling is correct, simplest or simplestt... Not knowing your context I do not know which it should be. But yeah, the function in the #ajax property is not defined in the context of this question.

  • thank you for your reply. I have edited the code and corrected the misspelled function for ajax callback but i till have the same problem. Nothing changes. I also cleared the cache and refreshed the page, nothing. Can try to run the code if you are able. – Ngatia Frankline Jul 6 '16 at 11:21
  • The next thing to do would be to put an exit() (not recommended), devel (for dpm or dsm), or use a debugger like xdebug (highly recommended) to step through the code, and ensure that the callback is being hit. – Kevin Jul 6 '16 at 13:12
  • Hi Kevin, i have debugged the form using devel and everything is okay. However, i used firebug to debug the response to the server and realised that the function does not return data. More help will be appreciated... – Ngatia Frankline Jul 7 '16 at 9:45
  • Since this looks like the same example given in the examples module, I would assume that it is working (given no typos) and more in how it is being shown on the page. What is the result if you move this to being a menu item callback instead of the first two lines of code? – Kevin Jul 7 '16 at 13:21
  • Hi Kevin, let me work on that...ill get back to you soon. – Ngatia Frankline Jul 7 '16 at 23:41

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