Changing a dropdown based on another one I've got a content type with a dropdown with some states. And I've got another list (radio buttons) which should change the dropdown based on the selected item. Is that somehow possible?

I've tried Conditional Fields, but that didn't do what I want. Maybe rules? I'm kind of newbie with Drupal.
If you want to do this hardcoded, you might try to use the #ajax property of the Form API

You can reload your second dropdown on change of the value of the first dropdown and change the value while reloading the form.

I made a little example to give you an idea :

$form['number'] = array(
  '#type' =&gt; 'select',
  '#title' =&gt; t('Select Number'),
  '#options' =&gt; array(
      0 =&gt; 1,
      1 =&gt; 2,
      2 =&gt; 3,
  ),
  '#default_value' =&gt; 0,
  '#ajax' =&gt; array(
    'callback' =&gt; 'ajax_replace_dropdown_default_value_callback',
    'wrapper' =&gt; 'wrapper-dropdown',
    'method' =&gt; 'replace',
    'effect' =&gt; 'fade',
  ),
);

$default_value = !empty($form_state['values']['number']) ? $form_state['values']['number'] : 0;

$form['open_closed'] = array(
  '#type' =&gt; 'select',
  '#title' =&gt; t('Open / Closed ?'),
  '#options' =&gt; array(
      0 =&gt; t('Open'),
      1 =&gt; t('Closed'),
      2 =&gt; t('Progress'),
  ),
  '#value' =&gt; $default_value,
  '#prefix' =&gt; '&lt;div id="wrapper-dropdown"&gt;',
  '#suffix' =&gt; '&lt;/div&gt;',
);

function ajax_replace_dropdown_default_value_callback($form, $form_state) {
  return $form['open_closed'];
}


In your case you will have to do it in a hook_form_alter and add the #ajax property to your first dropdown and add prefix and suffix to give the second dropdown the proper value.

You can also check this link about AJAX with the FORM API :