FormTestAutocompleteForm.php

<?php

namespace Drupal\form_test;

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

/**
 * Defines a test form using autocomplete textfields.
 *
 * @internal
 */
class FormTestAutocompleteForm extends FormBase {
    
    /**
     * {@inheritdoc}
     */
    public function getFormId() {
        return 'form_test_autocomplete';
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state) {
        $form['autocomplete_1'] = [
            '#type' => 'textfield',
            '#title' => 'Autocomplete 1',
            '#autocomplete_route_name' => 'form_test.autocomplete_1',
        ];
        $form['autocomplete_2'] = [
            '#type' => 'textfield',
            '#title' => 'Autocomplete 2',
            '#autocomplete_route_name' => 'form_test.autocomplete_2',
            '#autocomplete_route_parameters' => [
                'param' => 'value',
            ],
        ];
        $form['autocomplete_3'] = [
            '#type' => 'container',
            '#attributes' => [
                'class' => [
                    'container-inline',
                ],
            ],
            'autocomplete_3' => [
                '#type' => 'textfield',
                '#title' => 'Autocomplete 3',
                '#autocomplete_route_name' => 'form_test.autocomplete_1',
            ],
        ];
        return $form;
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitForm(array &$form, FormStateInterface $form_state) {
    }

}