所以我的Controller的代码如下:
private CommunityModelsContext dbCommunities = new CommunityModelsContext();
// GET: /Home/
public ActionResult Index()
{
//retrieve the Communities
ViewBag.Communities = dbCommunities.Communities.ToList();
return View();
}
我的视图具有启动部分视图的所有重要线条
<div id="LeftView" class="PartialView">@{Html.RenderPartial("CommunitiesPartial");}</div>
在Partial视图中,我正在尝试创建一个DropDownList(我还在学习,这是一个练习应用,只是为了看看我是否理解了asp.net教程中的概念),然后获取此实体列表,显示一个字段,从其他(“名称”和“ID”)
获取值@model BuildingManagement.Models.Community.Community
@Html.BeginForm("Index","CommunityController")
{
<div>
@Html.LabelFor(x => x.Name)
@Html.DropDownList("Community" , new SelectList(Model.Name,"id","Name"))
</div>
}
现在抛出一个NullReference异常,模型为null。索引页面中没有模型,它没有绑定任何模型,但是,数据是通过ViewBag发送的。
想法好吗?
答案 0 :(得分:3)
您的部分内容强烈输入模型(BuildingManagement.Models.Community.Community
)。所以你需要先将这个模型传递给主视图:
public ActionResult Index()
{
//retrieve the Communities
ViewBag.Communities = dbCommunities.Communities.ToList();
BuildingManagement.Models.Community.Community model = ... retrieve your model
return View(model);
}
然后由于您决定使用ViewBag而不是视图模型,您需要继续使用您在partial中的ViewBag中定义的值:
@Html.DropDownList("Community", new SelectList(ViewBag.Communities, "id", "Name"))
当然,更好的方法是使用视图模型:
public class CommunityViewModel
{
[DisplayName("Name")]
public int Id { get; set; }
public IEnumerable<SelectListItem> Communities { get; set; }
}
然后让控制器填充视图模型并将此视图模型传递给视图:
public ActionResult Index()
{
//retrieve the Communities
var communities = dbCommunities.Communities.ToList().Select(x => new SelectListItem
{
Value = x.Id.ToString(),
Text = x.Name
})
var model = new CommunityViewModel
{
Communities = communities
}
return View(model);
}
然后将您的视图和部分强类型添加到视图模型中:
@model CommunityViewModel
@using (Html.BeginForm("Index","CommunityController"))
{
<div>
@Html.LabelFor(x => x.Id)
@Html.DropDownListFor(x => x.Id, Model.Communities)
</div>
}