yii\mongodb\Query not found

Iam using MongoDb integration with Yii2.

when i was executing the code

public function actionSearch($sku) {

$query = new Query;


// compose the query


$query->select()


    ->from('products')


    ->where(['skus.sku' => $sku]);


$product = $query->all();





return $this->render('product', $product);

}

i got the ‘class not found’ error

“Fatal error: Class ‘yii\mongodb\Query’ not found”

how to slove it?