为什么DataBinding找不到存在的属性?

时间:2013-02-15 19:00:12

标签: c# asp.net data-binding

我已经宣布了一个类,但是当我尝试访问它的成员时,我收到以下错误:
 DataBinding:'reapTest.Toop'不包含名为'Rang'的属性。

WebForm1.aspx.cs:

namespace reapTest {

    public class Toop {
        public string Rang;
        public int Gheymat;
    }

    public static class MyData {

        public static Toop[] TP = new Toop[] { new Toop() { Rang = "Ghermez", Gheymat = 100 }, new Toop() { Rang = "Yellow", Gheymat = 44 } };
        public static Toop[] RT() {
            return TP;
        }

    }

    public partial class WebForm1 : System.Web.UI.Page {
        protected void Page_Load(object sender, EventArgs e) {

        }
    }
}

WebForm1.aspx:

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="reapTest.WebForm1" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>

        <asp:Repeater ID="Repeater1" runat="server" DataSourceID="ObjectDataSource1">
            <ItemTemplate>
                <%#Eval("Rang")%>
            </ItemTemplate>
        </asp:Repeater>

        <asp:ObjectDataSource runat="server" ID="ObjectDataSource1" SelectMethod="RT" TypeName="reapTest.MyData"></asp:ObjectDataSource>
    </div>
    </form>
</body>
</html>

1 个答案:

答案 0 :(得分:7)

我相信这是因为它正在寻找一个名为Rang的文字属性。您有一个名为Rang的字段,但这与属性不同,以及:

编辑:代码示例

public class Toop {

     // These values are *fields* within the class, but *not* "properties." 
     private string m_Rang; // changing these field decls to include m_ prefix for clarity
     private int m_Gheymat; // also changing them to private, which is a better practice

     // This is a public *property* procedure
     public string Rang     
     {
         get
         {
             return m_Rang;
         }
         set
         {
             m_Rang = value;
         }
     }
}

字段和属性是相关的,属性为每个类的实例的“私有”字段数据提供公共“包装”机制。但重要的是要注意它们是独立的概念,而不是可互换的。仅仅具有字段声明(在某些对象用语中也称为成员)不会将其作为属性公开。请注意@FrédéricHamidi所说的内容 - 文档说明"value of the expression parameter must evaluate to a public **property**"(强调我的)。

正如本摘录直接来自Microsoft 所述,EVAL,无论如何,都必须拥有属性

enter image description here

希望这会有所帮助。