Controller

public function actionSlider()
    {

        $model = new TblSlider();

        $model->created_by = Yii::$app->user->identity->name;
        $model->created_date = date('Y-m-d H:i:s');


        if ($model->load( Yii::$app->request->post())) {

            $fileImage = UploadedFile::getInstance($model, 'image');

            $ext = end((explode(".", $fileImage->name)));

            $model->image = Yii::$app->security->generateRandomString().".{$ext}";

            $path = Yii::$app->basePath . '/web/template/upload/slider/' . $model->image;

            if($model->save()){
                $fileImage->saveAs($path);
                return $this->refresh();
            }
        }


        return $this->render('slider', [
            'model' => $model,
        ]);
    }