CompositeFormElementTrait.php

<?php

namespace Drupal\Core\Render\Element;


/**
 * Provides a trait for radios, checkboxes, and similar composite form elements.
 *
 * Any form element that is comprised of several distinct parts can use this
 * trait to add support for a composite title or description.
 */
trait CompositeFormElementTrait {
    
    /**
     * Adds form element theming to an element if its title or description is set.
     *
     * This is used as a pre render function for checkboxes and radios.
     */
    public static function preRenderCompositeFormElement($element) {
        // Set the element's title attribute to show #title as a tooltip, if needed.
        if (isset($element['#title']) && $element['#title_display'] == 'attribute') {
            $element['#attributes']['title'] = $element['#title'];
            if (!empty($element['#required'])) {
                // Append an indication that this field is required.
                $element['#attributes']['title'] .= ' (' . t('Required') . ')';
            }
        }
        if (isset($element['#title']) || isset($element['#description'])) {
            // @see #type 'fieldgroup'
            $element['#attributes']['id'] = $element['#id'] . '--wrapper';
            $element['#theme_wrappers'][] = 'fieldset';
            $element['#attributes']['class'][] = 'fieldgroup';
            $element['#attributes']['class'][] = 'form-composite';
        }
        return $element;
    }

}