Disable row in Drupal tableselect

When you use the tableselect element there may be reasons you want to make a row not selectable:

• Permissions
• Missing properties on the element
• Or any other reason to not make a row selectable

I had to do this recently and thought it should be a easy thing to do, since all form elements seems to support the #disabled property.

A tableselect element looks something like this:

$form['table'] = [
  '#type' => 'tableselect',
  '#multiple' => FALSE,
  '#header' => [
    'name' => 'Name',
    'age' => 'Age',
  ],
  '#options' => $options,
  '#empty' => 'No items available',
];

And then each entry (in $options) would look like:

$options['anders'] = [ // knowing the key is important for disabling.
  'name' => [
    '#markup' => 'Anders',
  ],
  'age' => [
    '#markup' => 30,
  ],
];

You would think the way to disable a row is to just add '#disabled' => TRUE; to the option entry, but no, nothing happens.

To actually disable a row you would need to target the same key outside the #options array. Like this:

$form['table']['anders']['#disabled'] = TRUE; // Added directly to tableselect element.

In my opinion this is quite confusing.