数据插入失败，却又获取不到 errors？ [ 2.0 版本 ]

我想给数据库的部分表做一个统一的查删增改的接口，用了一个Api类继承的ActiveRecord，根据post数据动态确定表名，但是遇到了添加不进数据但是又获取不到errors的问题，请问能帮忙看看吗？

$this->post = json_decode(file_get_contents('php://input'), true) ?? json_decode('{"_csrf":"csrf","table":"question","tableOp":"questionManage","operate":"add","data":"{\"type\":\"不定项选择题\",\"title\":\"asdf\",\"image\":[],\"selectionList\":\"\",\"selection0\":\"\",\"selection1\":\"\",\"selection2\":\"\",\"selection3\":\"\",\"selection4\":\"\",\"selection5\":\"\",\"selection6\":\"\",\"selection7\":\"\",\"answer\":\"qerqe\",\"answerOrder\":true,\"ratio\":0}"}', true);//测试用数据
//0.table
$this->table = $this->post['table'];
$this->api = new Api();
$this->api::$tableName = $this->table;//动态确定表名

//1.data
$data = json_decode($this->post['data'], true);
$serverData = $this->translateDataB2S($data);//准备数据

//2.api
//$this->api = new Api();
//$this->api::$tableName = $table;

//3.operate and response
$this->api->attributes = $serverData;
if(!$this->api->save())
{
var_dump($this->api->getErrors());//问题就在这里，插入不了数据库，也不知都是什么原因，这一行打印出来是空数组
var_dump($this->api->save());//bool(false)
}
//echo json_encode($this->translateDataS2B($this->api->attributes));