关于Laravel-admin 的上传图片，提交数据为空

在Laravel-admin 里做了一个图片上传的功能，但现在出现这么个问题。

表单是这样写的

<?php

namespace App\Admin\Forms\Blogers;

use Encore\Admin\Widgets\Form;
use Illuminate\Http\Request;
use App\Admin\Models\CommonBloger;

class admincp_bloger_Bloger extends Form
{
    public function __construct()
    {
        $this->title = trans('admin.blogers.bloger.table_name_Bloger');
        parent::__construct();
    }

    /**
     * The form title.
     *
     * @var  string
     */
    public $title;

    /**
     * Handle the form request.
     *
     * @param  Request $request
     *
     * @return  \Illuminate\Http\RedirectResponse
     */
    public function handle(Request $request)
    {
        $validateRules = [
            'avatar' => '',
            'birth' => '',
            'gender' => '',
            'qq' => '',
            'qqgroup' => '',
            'wechat' => '',
            'email' => '',
            'college' => '',
            'occupation' => '',
            'workplace' => '',
            'residence' => '',
            'autograph' => '',
        ];
        $this->validate($request,$validateRules);
        $data = $request->except('_token');

        foreach($data as $skey => $svalue)
        {
            CommonBloger::set($skey, $svalue);
        }

        CommonBloger::setcache();

        admin_success(trans('admin.update_succeeded'));

        return back();
    }

    /**
     * Build a form here.
     */
    public function form()
    {
        $this->image('avatar', trans('admin.blogers.bloger.bloger_avatar'));
        $this->date('birth', trans('admin.blogers.bloger.bloger_birth'))->setWidth(2, 2);
        $this->select('gender', trans('admin.blogers.bloger.bloger_gender'))->options([trans('admin.blogers.bloger.gender.1') => trans('admin.blogers.bloger.gender.1'), trans('admin.blogers.bloger.gender.2') => trans('admin.blogers.bloger.gender.2'), trans('admin.blogers.bloger.gender.3') => trans('admin.blogers.bloger.gender.3')])->setWidth(2, 2);
        $this->text('qq', trans('admin.blogers.bloger.bloger_qq'))->rules('nullable|numeric')->setWidth(2, 2);
        $this->text('qqgroup', trans('admin.blogers.bloger.bloger_qqgroup'))->setWidth(2, 2);
        $this->text('wechat', trans('admin.blogers.bloger.bloger_wechat'))->setWidth(2, 2);
        $this->email('email', trans('admin.blogers.bloger.bloger_email'))->setWidth(2, 2);
        $this->text('college', trans('admin.blogers.bloger.bloger_college'))->setWidth(2, 2);
        $this->text('occupation', trans('admin.blogers.bloger.bloger_occupation'))->setWidth(2, 2);
        $this->text('workplace', trans('admin.blogers.bloger.bloger_workplace'))->setWidth(2, 2);
        $this->text('residence', trans('admin.blogers.bloger.bloger_residence'))->setWidth(2, 2);
        $this->text('autograph', trans('admin.blogers.bloger.bloger_autograph'))->setWidth(3, 2);
        $this->disableReset();
    }

    /**
     * The data of the form.
     *
     * @return  array $data
     */
    public function data()
    {
        return [
            'avatar' => CommonBloger::get('avatar'),
            'birth' => CommonBloger::get('birth'),
            'gender' => CommonBloger::get('gender'),
            'qq' => CommonBloger::get('qq'),
            'qqgroup' => CommonBloger::get('qqgroup'),
            'wechat' => CommonBloger::get('wechat'),
            'email' => CommonBloger::get('email'),
            'college' => CommonBloger::get('college'),
            'occupation' => CommonBloger::get('occupation'),
            'workplace' => CommonBloger::get('workplace'),
            'residence' => CommonBloger::get('residence'),
            'autograph' => CommonBloger::get('autograph'),
        ];
    }
}

filesystems里

'admin' => [
            'driver' => 'local',
            'root' => public_path('upload'),
            'visibility' => 'public',
            'url' => '/upload/avatar/',
        ],

admin里

'upload' => [

        // Disk in `config/filesystem.php`.
        'disk' => 'admin',

        // Image and file upload path under the disk above.
        'directory' => [
            'image' => 'images',
            'file'  => 'files',
        ],
    ],