文件上传的时候应用的类文件找不到 [ 求助交流 ]

model层：

<?php
    namespace app\models;
    use Yii;
    use yii\base\model;
    use yii\db\ActiveRecord;
    use yii\web\UploadedFile;
    
    class Upload extends Model {
        public $file;
        public function rules(){
            return [
                [['file'],'file','extensions' => 'jpg, png,jpeg', 'mimeTypes' => 'image/jpeg, image/png, image/jpeg','skipOnEmpty' => false],
            ];
        }
    }
?>

控制器层：

public function actionLoad(){
    $upload=new Upload;
    $request=Yii::$app->request;
    if($request->isPost){
        //echo 'a';die;
        $upload->file=UploadedFile::getInstance($upload,'file');
        //print_r($upload);die;
        if($upload->file && $upload->validate()){
            $upload->file->saveAs('uploads/' . $upload->file->baseName . '.' . $upload->file->extension);
        }else{
            echo '<script>alert("格式不正确")</script>';
            die;
        }
    }
    return $this->render('upfile',['model'=>$upload]);
}

视图层：

<?php
    use yii\helpers\Html;
    use yii\bootstrap\ActiveForm;
?>

<?php $form = ActiveForm::begin(['options' => ['enctype' => 'multipart/form-data']]) ?>

<?= $form->field($model, 'file')->fileInput()->label('选择文件') ?>

<button>Submit</button>

<?php ActiveForm::end() ?>

去封装一下比较好，要不然每次用都要这样写，麻烦