larave连接mongodb数据库 在$this->auth->attempt 时报错

Argument 1 passed to Illuminate\Auth\EloquentUserProvider::validateCredentials() must be an instance of Illuminate\Contracts\Auth\Authenticatable, instance of App\Model\Admin given, called in D:\phpStudy\WWW\chengmi\backend-chengmi-com\vendor\laravel\framework\src\Illuminate\Auth\Guard.php on line 390 and defined