Drupal8:如何基于Ajax回调生成选项

name: 'My Module'
type: module
description: 'Custom module for generating options using Ajax callback in Drupal 8'
core_version_requirement: ^8 || ^9
package: Custom
dependencies:
  - drupal:core

mymodule.module文件：

<?php

use Drupal\Core\Ajax\AjaxResponse;
use Drupal\Core\Ajax\ReplaceCommand;
use Drupal\Core\Form\FormStateInterface;

/**
 * Implements hook_menu().
 */
function mymodule_menu() {
  $items['mymodule/ajax-options'] = [
    'title' => 'Ajax Options',
    'description' => 'Ajax callback to generate options',
    'page callback' => 'mymodule_ajax_options_callback',
    'type' => MENU_CALLBACK,
    'access arguments' => ['access content'],
  ];

  return $items;
}

/**
 * Ajax callback to generate options.
 */
function mymodule_ajax_options_callback() {
  $response = new AjaxResponse();

  // Generate your options here.
  $options = [
    'option1' => 'Option 1',
    'option2' => 'Option 2',
    'option3' => 'Option 3',
  ];

  // Return the options as HTML.
  $response->addCommand(new ReplaceCommand('#options-container', theme('item_list', ['items' => $options])));

  return $response;
}

$form['my_element'] = [
  '#type' => 'select',
  '#title' => 'My Element',
  '#options' => [],
  '#ajax' => [
    'callback' => 'mymodule_ajax_options_callback',
    'wrapper' => 'options-container',
    'effect' => 'fade',
  ],
];

$form['options_container'] = [
  '#type' => 'container',
  '#attributes' => [
    'id' => 'options-container',
  ],
];