Question

javascript无法从网络方法中获取价值。

对于位于CallMe（）中的s值，它表示未定义。

我的目标是从Web方法获取一个对象....使用js中的数据..

我缺少什么_？

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Web.Script.Services;

public partial class _Default : System.Web.UI.Page 
{
    Label lblGeneral;
    protected void Page_Load(object sender, EventArgs e)
    {
        lblGeneral = textMessager;
    }
    [System.Web.Services.WebMethod]
    [ScriptMethod(ResponseFormat = ResponseFormat.Json)]
    public static string ShowMessage()
    {

        return ExternalManager.Write();
    }
}

JS

// JScript File
function CallMe()
 {    
     // call server side method
     var s = PageMethods.ShowMessage();
     s = eval(s);
 }



(function() {
var status = true;
var fetchService = function() {

           if(status){
             CallMe();
            status = false;
            }


            setTimeout(fetchService, 5000);
           status = true;

        }

window.onload = fetchService;
}())

**** Util类******

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Web.Script.Services;
using System.Web.Script.Serialization;
/// <summary>
/// Summary description for ExternalManager
/// </summary>
public class ExternalManager
{
    public ExternalManager()
    {
        //
        // TODO: Add constructor logic here
        //
    }
    public static string Write()
    {
        string s = "Okay Buddy" + DateTime.Today.ToLongDateString();
        JavaScriptSerializer jss = new JavaScriptSerializer();
        string serializedPerson = jss.Serialize(s);
        return  s;
    }
}

二手技术：启用了Asp.net 2.0 + Ajax C＃

Answer 1

这是一个AJAX电话。你不能写：

var s = PageMethods.ShowMessage();

并期望立即使用s变量，因为调用是异步的（它会立即返回，但结果仅在服务器响应后才可用）。您需要使用回调。这是一个完整的工作示例：

<%@ Page Language="C#" %>
<%@ Import Namespace="System.Web.Services" %>
<%@ Import Namespace="System.Web.Script.Services" %>
<script type="text/C#" runat="server">
    [WebMethod]
    [ScriptMethod(ResponseFormat = ResponseFormat.Json)]
    public static string ShowMessage()
    {
        return "Okay Buddy" + DateTime.Today.ToLongDateString();
    }
</script>
<!DOCTYPE html>
<html>
<head>
    <title>Test</title>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <script type="text/javascript">
        function CallMe() {
            // call server side method
            PageMethods.ShowMessage(function (result) {
                alert(result);
            });
        }

        (function() {
            var status = true;
            var fetchService = function () {
                if (status) {
                    CallMe();
                    status = false;
                }
                setTimeout(fetchService, 5000);
                status = true;
            }

            window.onload = fetchService;
        }());
    </script>
</head>
<body>
    <form id="form1" runat="server">
        <asp:ScriptManager ID="scm" runat="server" EnablePageMethods="true" />
    </form>
</body>
</html>

另请注意，您不应手动使用JavaScriptSerializer。它由PageMethods内部使用。在ShowMessage方法中，您还可以返回复杂对象。

如果方法有两个参数，你可以在成功和错误回调之前传递它们：

PageMethods.ShowMessage('param1', 'param2', onSucceed, onError);

使用json或其他convient类返回对象值

1 个答案: