Yii2: Conditional Validator always returns required

Question

I am trying to use Yii2\'s conditional validator as given in the guide like:

Model code

public function rules()
{
   // $discharged = function($model) {          


        

Answer 1

['package_id_fk', 'required', 'when' => function($model) {return $model->type == 'PACKAGE';}, 'enableClientValidation' => false],

It works for me.