When we build a form with text_format field in Drupal 8, images inserted in ckeditor is temporary and will be deleted 6 hours after cron by default.

    $form['content'] = [
      '#type' => 'text_format',
      '#title' => 'Content',
      '#format' => 'full_html',
      '#expected_value' => [
        'value' => 'Text value',
        'format' => 'plain_text',
      ],
    ];

To fix this issue, I write a patch and execute that patch at the end of form submit.

1. 管理匿名用户Form页面缓存

use Drupal\Core\Cache\Cache;

// 在匿名用户可以访问的表单里加入下面逻辑，包括列表页面和具体的查看页面

    $form['#cache']['tags'] = ['your_custom_tag_name'];

// 在写入逻辑里让缓存失效
    Cache::invalidateTags(['your_custom_tag_name']);

2. 禁用匿名用户Form页面缓存

在<module>.routing.yml文件路由定义里增加no_cache: 'TRUE'可禁用缓存

内核升级不时遇到这个错误，下面是解决的办法：
https://www.drupal.org/project/file_entity/issues/3056070
https://www.drupal.org/project/file_entity/issues/2914935#comment-13110657

本教程不讲安装，不讲CMS部分，直接讲述如何编写Drupal 9模块。部分内容还是基于Drupal 8的，但基本也适用于Drupal 9。

1. Coder: 检查代码是否符合规范
2. Examples: 扩展编写例子

Drupal 8 Site Building tutorial

Drupal 8

Creating custom modules

1. 先安装一个RESTUI模块
2. 启用配置好之后可以访问GET接口，例如：http://cto.eguidedog.net/node/241?_format=json

3. POST接口，例如：curl -H "Content-Type: application/json" -X POST -d '{"type":[{"target_id":"braille_printing_application"}],"title":[{"value":"test2"}],"field_address":[{"value":"addr2"}],"field_name":[{"value":"name2"}],"field_phone":[{"value":"phone2"}],"field_zipcode":[{"value":"zipcode2"}]}' http://cto.eguidedog.net/entity/node

简单得超乎想象！

https://www.drupal.org/node/2101565

个人遇到两个坑：

1. Drupal 8不能再像Drupal 7那样通过arg获取参数了。下面是获取参数的一个例子：

   

    $node = \Drupal::routeMatch()->getParameter('node');
    if ($node)
      $nid = $node->id();

2. Drupal 8会自动缓存很多东西，如果不声明缓存上下文，那么block的内容就相当于静态的。指定缓存的方法是给返回的元素增加以下属性：

'#cache' => array('contexts' => array('url')),

First, it's really a bad idea to use Drupal 8 beta version on production site like me. Because Drupal 8 beta release do not provide a way to upgrade between beta versions. The database and API are not frozen at all.

If you are unlucky like me, you can try following steps: