Why adding form element in ajax callback doesn't work (ref. FormAPI-52)

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Last seen: 9 years 4 weeks ago
Joined: 2013-05-07

Reference to Drupal 7 Dev Core > Form API > Chapter 52: Using the #ajax
(Link: https://buildamodule.com/video/drupal-7-development-core-concepts-how-to...)

The tutorial trying to implement ajax for adding checkbox after select the OS select field.

I tried to modify this a little by move the code block of following...

if (isset($form_state['values']['os'])) { // Fixed this line, was throwing an error in the original video code.
$form['computer_stats']['os_verify']['#type'] = 'checkbox';
$form['computer_stats']['os_verify']['#title'] = t('Are you sure you are using @os?', array('@os' => $form_state['values']['os']));

into the function input_os_verify_ajax_callback($form, $form_state)
before return them back.

It should work but it doesn't.

I wonder why it doesn't work? Since this method also return the $form element to the callback
and i think this way it make more sense.

Please help. Thank you.

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