C# MVC:通过选择ListItem我得到;System.NullReferenceException:对象引用未设置为对象的实例;错误
通过选择ListItem,我得到“System.NullReferenceException:对象引用未设置为对象的实例。”错误。我错了什么 这是我的xml:C# MVC:通过选择ListItem我得到;System.NullReferenceException:对象引用未设置为对象的实例;错误,c#,asp.net-mvc,C#,Asp.net Mvc,通过选择ListItem,我得到“System.NullReferenceException:对象引用未设置为对象的实例。”错误。我错了什么 这是我的xml: <?xml version="1.0" encoding="utf-8"?> <Artiesten> <Item ID_Artiest="509998" Artiest="-" Product="-" Land="" Plaats="" Website="" Genre="Onbekend" />
<?xml version="1.0" encoding="utf-8"?>
<Artiesten>
<Item ID_Artiest="509998" Artiest="-" Product="-" Land="" Plaats="" Website="" Genre="Onbekend" />
<Item ID_Artiest="970119" Artiest="(hed)p.e." Product="-" Land="" Plaats="" Website="" Genre="Onbekend" />
<Item ID_Artiest="970080" Artiest="(urusei) yatsura" Product="-" Land="" Plaats="" Website="" Genre="Noise" />
<Item ID_Artiest="1010302" Artiest="...and you will know us by the trail of dead" Product="-" Land="Verenigde Staten" Plaats="Austin (TX)" Website="" Genre="Noise" />
...
</Artiesten>
控制器由下一个下拉列表调用:
<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">
<% using (Html.BeginForm("Index", "Hitdossier", FormMethod.Post, new { id = "frmArtiest" })) %>
<% { %>
<table><tr><th width="1000" align="left">Selecteer artiest:</th></tr>
<tr>
<td><%= Html.DropDownList("ID_Artiest",
new SelectList(ViewBag.ArtiestenLijst, "Value", "Text"),
"-- Selecteer artiest --",
new
{
@onchange = "document.getElementById('frmArtiest').submit();"
})%>
</td>
</tr>
</table>
<br />
<br />
<div id="divPartialView">
<%= Html.Action("Detail_Hitdossier", new { AID_Artiest = ViewBag.ID_Artiest })%> <br />
</div>
<%} %>
</asp:Content>
Selecteer Artest:
谢谢请像这样初始化为新对象
ArtiestenLijst=新的ArtiestenLijst()代码>然后在控制器中使用后,您将以小写形式读取节点ID\u artiest,而xml显示为小写
改变
Value = artiest.Attribute("ID_artiest").Value,
到
如果artiest.Attribute(“ID\u artiest”)
导致空值,则读取属性值将引发空引用异常。在公共操作结果索引中,错误出现在以下行:==>选择新SelectListItem是否正确加载了XML文档?如果调试它,您能看到其中的元素吗?很抱歉,这是一个区分大小写的问题。。。但是谢谢你的回答,
<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">
<% using (Html.BeginForm("Index", "Hitdossier", FormMethod.Post, new { id = "frmArtiest" })) %>
<% { %>
<table><tr><th width="1000" align="left">Selecteer artiest:</th></tr>
<tr>
<td><%= Html.DropDownList("ID_Artiest",
new SelectList(ViewBag.ArtiestenLijst, "Value", "Text"),
"-- Selecteer artiest --",
new
{
@onchange = "document.getElementById('frmArtiest').submit();"
})%>
</td>
</tr>
</table>
<br />
<br />
<div id="divPartialView">
<%= Html.Action("Detail_Hitdossier", new { AID_Artiest = ViewBag.ID_Artiest })%> <br />
</div>
<%} %>
</asp:Content>
Value = artiest.Attribute("ID_artiest").Value,
Value = artiest.Attribute("ID_Artiest").Value,