multiselect.md

Working with the multiselect widget

We often need to select multiple options from a <select> field. However, the default browser widget for <select multiple> is not intuitive. So we have created a custom widget that is easier to use.

This widget can be used by setting the block_prefix attribute of a Symfony Form CollectionType / EntityType. You also have to set a data-placeholder attribute on the widget. This placeholder is only used in the interface as a disabled option. For instance, to display an "observers" field:

$form->add('observers', AppType\ActorType::class, [
    'multiple' => true,
    'by_reference' => false,
    'required' => false,
    'label' => new TranslatableMessage('tickets.observers'),
    'attr' => [
        'data-placeholder' => $this->translator->trans('forms.multiselect.select_actor'),
    ],
    'block_prefix' => 'multiselect',
]);