How to disable the first option of select form element

Question

I created a custom module that contains a form with select element I tried to disable the first option like this, but failed to get it work

'#options' => $terms,
                '#empty_option' => '- Select category -',
                '#empty_value' => 'none',
                '#disabled_values' => array('none'),

How could this be achieved without removing the option?

Answer 1

There is a contrib module that can help: Form Options Attributes

This module adds the ability to specify attributes for individual options on Drupal Form API elements of the types: select, checkboxes, and radios.

Also Jaime Calvo's answer about writing:

['#options']['my disabled option'] = [];

Doesn't really create a disabled option, but an empty optgroup.

Answer 2

Drupal by default doesn't allow for this, so you'll need to do two things:

1. Override theme_select()
2. Create your own callback the create the options
3. Change the way you define your select options in your form definition

Overriding theme_select():

function THEME_select($variables) {
  $element = $variables['element'];
  element_set_attributes($element, array('id', 'name', 'size'));
  _form_set_class($element, array('form-select'));

  return '<select' . drupal_attributes($element['#attributes']) . '>' . custom_form_select_options($element) . '</select>';
}

Create your own callback the create the options:

function custom_form_select_options($element, $choices = NULL) {
  if (!isset($choices)) {
    $choices = $element['#options'];
  }
  // array_key_exists() accommodates the rare event where $element['#value'] is NULL.
  // isset() fails in this situation.
  $value_valid = isset($element['#value']) || array_key_exists('#value', $element);
  $value_is_array = $value_valid && is_array($element['#value']);
  $options = '';
  foreach ($choices as $key => $choice) {
    if (is_array($choice) && !isset($choice['data'])) {
      $options .= '<optgroup label="' . check_plain($key) . '">';
      $options .= form_select_options($element, $choice);
      $options .= '</optgroup>';
    }
    elseif (is_object($choice)) {
      $options .= form_select_options($element, $choice->option);
    }
    else {
      $key = (string) $key;
      if ($value_valid && (!$value_is_array && (string) $element['#value'] === $key || ($value_is_array && in_array($key, $element['#value'])))) {
        $selected = ' selected="selected"';
      }
      else {
        $selected = '';
      }
      $options .= '<option value="' . check_plain($key) . '"' . $selected;
      if(is_array($choice) && isset($choice['disabled']) && $choice['disabled'])
      {
          $options .= ' disabled';
      }
      $choice = is_array($choice) && isset($choice['data']) ? $choice['data'] : $choice;
      $options .= '>' . check_plain($choice) . '</option>';
    }
  }
  return $options;
}

Change the way you define your select options in your form definition. Turn the option into an array with two keys:

1. data: The display value of the element
2. disabled: A boolean indicating whether to disable the element

Example:

$form['select'] = array(
  '#title' => t('Pick something'),
  '#type' => 'select',
  '#options' => array(
    'yes' => array('data' => t('Yes'), 'disabled' => TRUE),
    'no' => t('No'),
  ),
);

Answer 3

I prefer in this case use a single line of jQuery.

$("select option:first-child").attr("disabled", "true");

It adds the disabled attribute :

<option value="disabled_options" disabled="disabled">-- choice : --</option>

I would have preferred to do it with formApi but I think this is too much code for a basic thing.

Answer 4

If you just set an empty array as value the option will be disabled.

['#options']['my disabled option'] = [];

this option will get the name, 'my disabled option' and will be disabled.