将ID从父视图传递到部分视图，但失败了

Question

我想将user.Id传递到局部视图，以在局部视图中填充“ @ Html.EditorFor（model => model.UserID，新{@Value = id}）”。在此局部视图模型中，我得到的是null。父视图的代码是

@model KhanewalNews.Models.user
    @{ 
        int id = Model.id;
    }
@Html.Partial("AssignRoles",null, new ViewDataDictionary { { "id", id } });

@{
    ViewBag.Title = "MemberDetails";
    Layout = "~/Views/Shared/_DashboardLayout.cshtml";
}
//parent view implementation here

部分视图的代码是

@model KhanewalNews.Models.Role
    <script src="~/Scripts/jquery-1.8.2.min.js"></script>
    <script src="~/Scripts/jquery.validate.min.js"></script>
    <script src="~/Scripts/jquery.validate.unobtrusive.min.js"></script>
@{ 
    int id = (int)this.ViewData["id"];
}
    @using (Html.BeginForm())
    {
        @Html.AntiForgeryToken()
        @Html.ValidationSummary(true)

        <fieldset>
            <div class="editor-label">
                @Html.LabelFor(model => model.UserID)
            </div>
            <div class="editor-field">
                @Html.EditorFor(model => model.UserID, new { @Value = id })
                @Html.ValidationMessageFor(model => model.UserID)
            </div>
            <div class="editor-label">
                @Html.LabelFor(model => model.role1)
            </div>
            <div class="editor-field">
                @Html.DropDownListFor(m => m.role1, new SelectList(
                  new List<Object>{
                       new { value = "add" , text = "add"  },
                       new { value = "update" , text = "update" },
                       new { value = "delete" , text = "update"},
                        new { value = "super" , text = "super"}
                    },
                  "value",
                  "text"
           ))
                @Html.ValidationMessageFor(model => model.role1)
            </div>
            <p>
                <input type="submit" value="Create" />
            </p>
        </fieldset>
    }
    <div>
        @Html.ActionLink("Back to List", "Index")
    </div>

这在部分视图中引发异常，即“ System.NullReferenceException：'对象引用未设置为对象的实例。'”请指导我我错了。Controller

public ActionResult AssignRoles()
        {
            return View();
        }
        [HttpPost]
public ActionResult AssignRoles(Role r)
        {
            //implementation here
            return View();
        }
    public ActionResult MemberDetails(int id)
    {
        var userdetail = new user();
        var user = db.users.Where(x => x.id == id).FirstOrDefault();
        userdetail.username = user.username;
        return View(userdetail);
    }

Answer 1

public ActionResult MemberDetails(int id)
{
    var user = db.users.Where(x => x.id == id).FirstOrDefault();
    return View(user);
}