$reg->load(Yii::$app->request->post())public function actionRegistration()
{
$reg = new Registration();
if($reg->load(Yii::$app->request->post()) && $reg->validate()) {
exit('Валидация прошла!');
}
return $this->render('registration', ['reg' => $reg]);
}success: function(res){
alert(res)
},success: function(res){
console.log(res)
},$subQuery = Model::find()->from(...); // JSON_TABLE
$query = Model::find()->from($subQuery)->join(...);common/config/main-local.php для Advanced шаблона и в config/main-local.php для Basic шаблона.