FormTestDetailsContainsRequiredTextfieldForm.php

<?php

declare (strict_types=1);
namespace Drupal\form_test\Form;

use Drupal\Core\Form\FormBase;
use Drupal\Core\Form\FormStateInterface;

/**
 * Builds a form to test a required textfield within a details element.
 *
 * @internal
 */
class FormTestDetailsContainsRequiredTextfieldForm extends FormBase {
    
    /**
     * {@inheritdoc}
     */
    public function getFormId() : string {
        return 'form_test_details_form';
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state, $use_ajax = FALSE) : array {
        $form['meta'] = [
            '#type' => 'details',
            '#title' => 'Details element',
            '#open' => FALSE,
        ];
        $form['meta']['required_textfield_in_details'] = [
            '#type' => 'textfield',
            '#required' => TRUE,
            '#title' => 'Required textfield',
        ];
        $form['submit'] = [
            '#type' => 'submit',
            '#value' => 'Submit',
        ];
        if ($use_ajax) {
            $form['submitAjax'] = [
                '#type' => 'submit',
                '#value' => 'Submit Ajax',
                '#ajax' => [
                    'callback' => '::submitForm',
                    'event' => 'click',
                    'wrapper' => 'form-test-details-form',
                ],
            ];
        }
        return $form;
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitForm(array &$form, FormStateInterface $form_state) {
        return $form;
    }

}