使用Bootstrap fileInput上传图片，引用空值规则导致数据未写入数据库与规则错误问题 [ 2.0 版本 ]

使用Bootstrap fileInput扩展上传图片，在model的rules定义了空值验证（ 'skipOnEmpty' => false），上传图片后，文件有按新文件名上传至服务器，但文件名未写入数据库，且返回视图引发空值验证规则（如图一）

请教哪位大神，controller是哪里逻辑有问题，还是该怎么做好！

Controller文件
public function actionImage($id)

{
    $model = $this->findModel($id);
    $rootPath = "uploads/UserIdImage/";    //定义上传的根目录
    $oldFile = $rootPath . $model->image; //保存旧头像路径与文件名，上传新的文件后删除用

    if (Yii::$app->request->isPost) {
        $model->image = UploadedFile::getInstance($model, 'image');

        if ($model->image && $model->validate()) {
            $ext = $model->image->extension;
            $randName = "userid" . time() . rand(1000, 9999) . "." . $ext;
            $model->image->saveAs($rootPath . $randName);
            $model->image = $randName;
            unlink($oldFile);
            $model->save();
        }
    }
    return $this->render('image', ['model' => $model]);
}

Model文件
public function rules()

{
    return [
        ['status', 'default', 'value' => self::STATUS_ACTIVE],
        ['status', 'in', 'range' => [self::STATUS_ACTIVE, self::STATUS_DELETED]],
        [['email'], 'unique'],
        [['email'], 'required'],
        [['email'], 'email'],
        [['image'], 'file', 'maxSize' => 1024 * 1024, 'skipOnEmpty' => false],
    ];
}

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

<?= $form->field($model, 'image')->widget(FileInput::classname(), [

'options' => ['accept' => 'image/*'],

]);
?>

<?php ActiveForm::end() ?>