Hide controlled field with single option

Good idea, that could be an option as well. For our current use we'd like to not show anything to the user if they don't have to choose. Although, simply disabling the option would show the option which has been selected.

Ok this patch doesn't quite work, presumably because a select field can't be changed to a hidden (straight text) field and be expected to pass on the value in the correct format.

Will keep at it, any suggestions welcome.

Hiding it via CSS is what we've gone with. I've done this using a custom module but it could potentially be included in Dependent Fields (taking #1 into account).

An additional option "Not sure" is offered when there's more than one option to present to the user.

/**
 * Implementation of hook_form_alter().
 */
function MYMODULE_form_alter(&$form, $form_state, $form_id) {
  switch ($form_id) {
    case "MY_FORM_ID":   
      $form['#after_build'][] = 'MYMODULE_MYFORM_after_build';  
      break;
  }
}

/*
 * Modify CCK form elements on MYFORM
 */
function MYMODULE_MYFORM_after_build($form, &$form_state) {
  // Hide field when only one option
  $options = $form['field_controllerfield_ahah_wrapper']['field_controlledfield']['value']['#options'];
  if ((count($options) == 1) && end($options) != '- None -') {            
    $form['field_controllerfield_ahah_wrapper']['field_controlledfield']['#prefix'] .= '<div style="display: none;">';
    $form['field_controllerfield_ahah_wrapper']['field_controlledfield']['#suffix'] .= '</div>';
  } else {
    $form['field_controllerfield_ahah_wrapper']['field_controlledfield']['value']['#options']['Not sure'] = 'Not sure';       
  }
  return $form;
}