asp.net-mvc mvc 视图中的模型空引用异常
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Model Null reference exception in mvc view
提问by user2189168
The problem is getting null reference exception when passing data from controller to view
问题是在将数据从控制器传递到视图时获取空引用异常
I am Passing a model to the view from the controller like this:
我正在将模型从控制器传递给视图，如下所示：
{
ViewBag.PartId = id;
var viewmodel= new Orderviewmodelnew();
var order = new OrderMnagernew().GetSingleOrderField(id);
viewmodel.ProjectId=order.ProjectId;
return View(viewmodel);
}
And in the View I have code like this
在视图中我有这样的代码
@model DreamTrade.Web.BL.ViewModels.OrderViewModelnew
Home>Project @Model.ProjectID==null??//projected is of type guid
Customer :@(Model.CreatedBy??string.empty)
Project :@Model.ProjectID
@Model.ProjectDetail
CreatedBy:@Model.CreatedBy
Creation Date:@Model.CreationDate
CompletedBy :@Model.ModifiedBy
Completion Date:@Model.LastModified
@Model.Image
@Html.Action("OrderIndex", "Ordernew", new { PartId = Guid.Parse("C0497A40-2ADE-4B23-BA9F-1694F087C3D0") })
I have Tried like this
我试过这样
@if(Model.ProjectId==Null)
{/....}
In the controller i tried like this by not passing model if it is null
在控制器中，如果模型为空，我尝试通过不传递模型
var order = new OrderMnagernew().GetSingleOrderField(id);
if(order!=null)
{
viewmodel.ProjectId=order.ProjectId;
return View(viewmodel);
}
return View()
The problem with this the projectid in the view is showing exception.
视图中的 projectid 的问题是显示异常。
I Want to display empty string if it is null and show the remaining part..
如果它为空，我想显示空字符串并显示其余部分..
采纳答案by webdeveloper
This code is wrong:
这段代码是错误的：
@Model.ProjectID==null??string.empty
if ProjectIDis nullable type, you should write:
如果ProjectID是可空类型，你应该写：
@(Model.ProjectID ?? string.empty)
Added:
添加：
Replace:
代替：
return View()
with:
和：
return View(new Orderviewmodelnew())
because nullobject doesn't have any properties
因为null对象没有任何属性
回答by Nicholas Butler
By putting
通过把
@model DreamTrade.Web.DALNew.Source
at the top of your view, you're making a strongly-typed view which expects a model of that type.
在视图的顶部，您正在创建一个强类型视图，该视图需要该类型的模型。
However, in your controller, you're passing a model of type Orderviewmodel
但是，在您的控制器中，您正在传递一个类型的模型 Orderviewmodel
You need to make sure the model you pass to the view is of the right type.
您需要确保传递给视图的模型是正确的类型。
