How can I add css classes to specific symfony2 form choices?

Question

I could do this with Javascript, but I was wondering if I could add a css class to specific symfony2 form choices (not the choice field itself, but the individual choices).

For example I want to apply different css styles to individual 'option' tags inside a 'select'. I could only find a way to add a class to the tag.

Thanks in advance.

Answer 1

Add attributes like CSS styles to individual choices can nowadays be achieved with choice_attr, e.g.:

use Symfony\Component\Form\Extension\Core\Type\ChoiceType;
// ...

$builder->add('attending', ChoiceType::class, array(
    'choices' => array(
        'Yes' => true,
        'No' => false,
        'Maybe' => null,
    ),
    'choice_attr' => function($val, $key, $index) {
        // adds a class like attending_yes, attending_no, etc
        return ['class' => 'attending_'.strtolower($key)];
    },
));