Disabling tableselect element options

Problem/Motivation

There's no handy way to mark some rows as disabled for selection in a tableselect element.

Proposed resolution

Allow to pass an optional #disabled property in option. When an option has #disabled === TRUE, the corresponding checkbox will be disabled.

Workaround

Without this change there's still possible to disable certain rows:

1. Add an additional #process callback to the tableselect element. Note that you should add also the original processor:
   

   $form['my_table'] = [
     '#type' => 'tableselect',
     ...
     '#process' => [
       // This is the original #process callback.
       [Tableselect::class, 'processTableselect'],
       // Additional #process callback.
       [static::class, 'processDisabledRows'],
     ],
     ...
   ];
   

2. The additional #process callback:
   

   public static function processDisabledRows(array &$element): array {
     foreach (Element::children($element) as $key) {
       $element[$key]['#disabled'] = isset($element['#options'][$key]['#disabled']) ? $element['#options'][$key]['#disabled'] : FALSE;
     }
     return $element;
   }
   

3. Set the #disabled property to TRUE on the rows that you want to disable:
   

   $form['my_table'] = [
     '#type' => 'tableselect',
     ...
     '#options' => [
       'row1' => [
         'col1' => '1.1',
         'col2' => '1.2',
       ],
       // This row is disabled.
       'row2' => [
         'col1' => '2.1',
         'col2' => '2.2',
         '#disabled' => TRUE,
       ],
     ],
     ...
   ];
   

Remaining tasks

None.

User interface changes

API changes

A tableselect element can have disabled options.

Data model changes

None.

Release notes snippet

By adding a #disabled property set to TRUE, it's possible to prevent used by selecting certain options in a tableselect form element.

Initial report

Currently it is not possible to disable an option on a tableselect list.
Can we allow a Tableselect checkbox to be disabled on a specific option, like it currently is possible with the attribute and ajax parameters?