How to access an array property in the beforeSave method in yii?

Question

Yii

Good afternoon, such a problem:
in actionBeforeSave I do print_r($_POST) , it comes out:
Array
(
[Product] => Array
(
[NAME] => cookie
[params] => Array
(
[0] => 2
[1] => 3
[2] => 4
[3] => 5
[4] => 6
)
)
[yt0] => Create
)
BUT when I try to do print_r($this->params), then the output is an empty array, tell me how humanly you can refer to this property of the class.