laravel再使用事务时,redirect无效

public function store(UserRequest $request)

{
    //开启事务
    \DB::transaction(function () use ($request) {
        $role = $request->input('roles');
        //保存用户
        $user = User::create($request->except(['_token', 'roles', 'password_confirmation']));
        //赋予角色
        $result = $user->assignRole($role);
        if ($result) {
            alert()->success('用户添加成功!');
        } else {
            alert()->error('用户添加失败!');
        }
        return redirect()->route('user.index');
    });
}

请问各位大神如何才知道,事务执行成功?我这样子做redirect无效 数据是已经保存了!