请问怎么验证路由参数

Route::delete('members/{member}', 'MembersController@destroy')

例如我需要验证member路由参数，需要怎么验证？

public function rules()
    {
        switch($this->method())
        {
            case 'POST':
            case 'PUT':
            {
                return [
                    'member_type_id' => 'required|exists:member_types,id',
                    'fullname' => 'required',
                    'sex' => 'required',
                ];
            }
            case 'DELETE':
            {
                return [
                    'member' => ''//这样无法获取member参数，请问怎么才能验证此参数
                ];
            }
            default:
            {
                return [];
            };
        }
    }