显示某些角色的视图部分，并对未登录的用户隐藏导航按钮

Question

我在。net中为学校创建了一个MVC项目，并使用此代码仅向具有指定角色的特定用户显示视图的某些部分。

public ActionResult About()
    {
        if (User.IsInRole("Begeleider"))
        {
            var client = new WebClient();
            var jsonLeerlingen = client.DownloadString(new Uri("http://localhost:8080/projecten/api/leerlingen"));
            var leerlingen = Newtonsoft.Json.JsonConvert.DeserializeObject<IEnumerable<Leerling>>(jsonLeerlingen);
            ViewBag.Message = leerlingen;
        }
        return View();
    }

当我登录具有角色'Begeleider'的用户时，这是有效的，但是当我单击导航中的按钮时，我在cshtml中得到一个错误。这是合乎逻辑的，因为我在这里调用代码，但当我没有以正确的角色登录时无法访问它。但我该怎么解决呢?

@{
ViewBag.Title = "Evaluaties";
var leerlingen = List<ASPNetMVCExtendingIdentity2Roles.Domain.Leerling>)ViewBag.Message;
}
<h2>@ViewBag.Title.</h2>
<h4>Leerlingen</h4>
<table>
@foreach (var leerling in leerlingen)
{
    <tr>
        <td>@leerling.Naam</td>
        <td>@leerling.Email</td>
    </tr>
}
</table>
<h4>Evaluaties</h4>
@* Here shall be the same code as above but for a Leerling himself he'll only be able to see himself and his own Evaluation(Evaluatie), Haven't figuerd it out yet. *@

导航是这样的，最后一个li是不应该对未登录的用户可见的。

<div class="navbar-collapse collapse">
            <ul class="nav navbar-nav">
                <li>@Html.ActionLink("Home", "Index", "Home")</li>
                <li>@Html.ActionLink("Roles", "Index", "Roles")</li>
                <li>@Html.ActionLink("Evaluaties", "About", "Home")</li>
            </ul>
            @Html.Partial("_LoginPartial")
        </div>

Answer 1

我找到了这样的答案，所以只有当您登录时才能看到列表

<div class="navbar-collapse collapse">
            <ul class="nav navbar-nav">
                @if (Request.IsAuthenticated)
                {
                    <li>@Html.ActionLink("Home", "Index", "Home")</li>
                    <li>@Html.ActionLink("Roles", "Index", "Roles")</li>
                    <li>@Html.ActionLink("Evaluaties", "About", "Home")</li>
                }
                else
                {
                    <li>@Html.ActionLink("Home", "Index", "Home")</li>
                    <li>@Html.ActionLink("Roles", "Index", "Roles")</li>
                }
            </ul>
            @Html.Partial("_LoginPartial")
        </div>

Answer 2

为操作方法使用授权属性:

//you may use it without role name: [Authorize]
[Authorize(Roles = "Begeleider")]
public ActionResult About()
    {
            var client = new WebClient();
            var jsonLeerlingen = client.DownloadString(new Uri("http://localhost:8080/projecten/api/leerlingen"));
            var leerlingen = Newtonsoft.Json.JsonConvert.DeserializeObject<IEnumerable<Leerling>>(jsonLeerlingen);
            ViewBag.Message = leerlingen;
        return View();
    }

如果你想隐藏非角色用户的链接，使用:

if(User.IsInRole("Evaluaties")){
<li>@Html.ActionLink("Evaluaties", "About", "Home")</li>
}