yii2 beforeSave() method

    public function beforeSave($insert)
    {
        if (parent::beforeSave($insert)) {
            if ($this->isNewRecord) {
                $this->author = \Yii::$app->user->identity->id;
                $this->create_date = time();
            }
            else {
                $this->author=\Yii::$app->user->identity->id;
                $this->update_date=time();

            }

        }

        return true;
    }