即使上传了文件，Laravel Input：：hasFile('image') 也会返回 false

I have a Form field for an Image upload, which I open with 'files' => true, like so:

{{ Form::label('image', 'Image') }}
{{ Form::file('image') }}

在我的控制器中，我想判断是否上传了文件，并对其进行处理:

if (Input::hasFile('image')){
        $in_path = 'img/';
        $in_extension = Input::file('image')->getClientOriginalExtension();
        $filename = Input::get('name').".".$in_extension;
        Input::file('image')->move($in_path, $filename);
        $user->image = $filename;
    }

但是Input::hasFile总是返回错误，我不知道为什么.

Input::file('image');

结果如下:

Symfony\Component\HttpFoundation\File\UploadedFile Object
(
[test:Symfony\Component\HttpFoundation\File\UploadedFile:private] => 
[originalName:Symfony\Component\HttpFoundation\File\UploadedFile:private] => test.JPG
[mimeType:Symfony\Component\HttpFoundation\File\UploadedFile:private] => application/octet-stream
[size:Symfony\Component\HttpFoundation\File\UploadedFile:private] => 0
[error:Symfony\Component\HttpFoundation\File\UploadedFile:private] => 1
[pathName:SplFileInfo:private] => 
[fileName:SplFileInfo:private] => 
)

I have tested around with another picture for another User and this works fine. I don't get why this is working for some Users and for some others not.

这个问题的原因还有哪些？