“Setting unknown property” error when adding properties to instantiated object - yii2

I’m using yii2 and I wanted to add some extra attributes and validation rules for them to the model after I call $model->createValidators().

But when I tried with the below code, at the line “$this->{$attr->code} = null”, it’s throwing the error: “Setting unknown property”.

public function rules(){

    $rules = [];

    if(!is_null($this->attributeSetId)){ // set the rules for custom attributes

        foreach($this->attributeSet->attributeGroups as $group){

            foreach($group->productAttributes as $attr){  


                    $rules[] = [[$attr->code], 'required'];


                    $rules[] = [[$attr->code], 'safe'];

                $this->{$attr->code} = null; // trying to set new property to the model (this is the line causing error)




    return array_merge([

        [['attributeSetId', 'parent', 'typeId'], 'integer'],

        [['attributeSetId'], 'required'],

    ], $rules);


I know properties can be declared to an object after we instantiate it using the above method but it’s not working in the above mentioned case.

When I manually set the properties as: “public $propertyName;” at the starting of the model, it’s working perfect but in my case, the properties list is dynamic.

Can someone throw some light on this please?