对象引用未设置为对象的实例在视图中使用foreach循环时。 [英] Object reference not set to an instance of an object While using foreach loop in a View.

问题描述

您好我正在创建一个View并在其中调用Partial View，如下所示

 @ {
 //ViewBag.Title =; 
 Layout =〜/ Views / Shared / _restLayout.cshtml; 
} 
 
 
< div class =row sidebar_left> 
< div class =column_center> 
< div id =main_contentclass =col-sm-9> 
 @RenderBody（）
< / div> 
< / div> 
 
< div class =column_left column col-sm-3> 
< div class =widget widget__collections> 
< h3 class =widget_header>收藏品< / h3> 
 @ Html.Partial（categoryPartial）
< / div> 
< / div> 
< / div> 

当我运行应用程序时，它会抛出错误对象引用未设置为实例一个对象在foreach循环中。

 @model IEnumerable< fashionHub_new.Models.category> 
 
< div class =widget_content> 
< ul class =list> 
 @foreach（ViewData [Category]中的var项目为List< fashionHub_new.Models.category>）
 {
< li class =underwear-socks> 
< a href =＃title =ABC> ABC< / a> 
< / li> 
} 
< / ul> 
< / div> 

请在下方找到我的控制器

 public ActionResult Index（）
 {
 ViewData [Category] = _businessLayer.ViewAllCategory（）。ToString（）; 
 return View（）; 
} 

请提供相同的解决方案。

解决方案

 ViewData [Category] = _businessLayer.ViewAllCategory（）。ToString（）; 

ViewData [Category]被设置为一个字符串。

 ViewData [Category]如List< fashionHub_new.Models.category>） 

as尝试将ViewData [Category]（字符串）转换为List< category>如果不能，则返回null。由于您的ViewData是一个字符串，它将返回null。您可能需要在控制器中执行此操作

 ViewData [Category] = _businessLayer.ViewAllCategory（）。ToList（）; 

Hi I am creating a View and calling Partial View in it as below

@{
    //ViewBag.Title = "";
    Layout = "~/Views/Shared/_restLayout.cshtml";
}


<div class="row sidebar_left ">
    <div class="column_center">
        <div id="main_content" class="col-sm-9">
            @RenderBody()
        </div>
    </div>

    <div class="column_left column col-sm-3">
        <div class="widget widget__collections">
            <h3 class="widget_header">Collections</h3>
            @Html.Partial("categoryPartial")
        </div>
    </div>
</div>

When I run the application it throws an error "Object reference not set to an instance of an object " in foreach loop.

@model IEnumerable<fashionHub_new.Models.category>

<div class="widget_content">
    <ul class="list">
        @foreach (var item in ViewData["Category"] as List<fashionHub_new.Models.category>)
        {
            <li class="underwear-socks">
                <a href="#" title="ABC">ABC</a>
            </li>
        }
    </ul>
</div>

Please find my controller below

public ActionResult Index()
        {
            ViewData["Category"] = _businessLayer.ViewAllCategory().ToString();
            return View();
        }

Please provide the solution for the same.

解决方案

ViewData["Category"] = _businessLayer.ViewAllCategory().ToString();

ViewData["Category"] is being set to a string.

ViewData["Category"] as List<fashionHub_new.Models.category>)

the "as" tries to convert ViewData["Category"] (a string) as a List<category> and if it can't it returns null. As your ViewData is a string it will return null. You probably need to do this instead in your controller

ViewData["Category"] = _businessLayer.ViewAllCategory().ToList();

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