Sample

$post = Yii::$app->request->post();

$model = new DynamicModel(['mid' => null, 'email' => null]);
$model->addRule(['mid', 'email'], 'required');
$model->load($post);
if($model->validate()) {
    return ["message" => "Validation pass!"];
} else {
    return ["message" => "Validation fail. Please check your input!"];
}