Why in yii2 dataProvider does not see NULL?

Question

Yii

Hi why doesn't dataProvider see 'parent_id' => NULL ?
here is the complete query

$searchModel = new TicketSearch();
 $dataProvider = $searchModel->search(Yii::$app->request->queryParams);
        $dataProvider->query->andFilterWhere(['user_id' => Yii::$app->user->id, 'parent_id' => NULL]);

Answer 1

andFilterWhere seems to work when data is specified, it makes it easier to work with empty search fields, in this case already use andWhere