ajaxpro两级联动出现错误

如何在单击按钮时，第二级DropDownList还能保持刚才选中的项，并且如何才能取到第二级DropDownList的值（在.cs代码中）

因为你点击按钮的同时页面就刷新了，就会重新对你的DropDownList绑定

把你选择的第一个下拉值通过URL传递过来，然后在page_load里得到。申明public个全局变量，选种第一个下拉框的值，然后用JS。在body onload事件里重新调用你的级联代码一次就可以了。

得加一个隐藏域
保存第二级的droplist的值然后现加载事件中选隐藏域的那一项

得到值　可以做到了，但是如何在单击按钮后，第二级DropDownList还能保持刚才选中的项？
把你选择的第一个下拉值通过URL传递过来，然后在page_load里得到。申明public个全局变量，选种第一个下拉框的值，然后用JS。在body onload事件里重新调用你的级联代码一次就可以了。
看不明白，能给些详细代码吗

请看如下代码：
页面：
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="DropDownListTest.aspx.cs" Inherits="AjaxTest.DropDownListTest" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>无标题页</title>
</head>
<body onload="_OnLoad('<%=m_selectedValue%>');">
    <script language="javascript" type="text/javascript">
    
    </script>
    <form id="form1" runat="server">
    <div>
        From:
        <asp:DropDownList ID="DropDownList1" runat="server">
            <asp:ListItem Value="">请选择</asp:ListItem>
            <asp:ListItem Value="1">1</asp:ListItem>
            <asp:ListItem Value="2">2</asp:ListItem>
        </asp:DropDownList>
        To:
         <asp:DropDownList ID="DropDownList2" runat="server">
        </asp:DropDownList>
        <br />
        <asp:Button ID="Button1" runat="server" Text="刷新"/>
    </div>
    </form>
</body>
</html>
后台代码：
using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;namespace AjaxTest
{
    public partial class DropDownListTest : System.Web.UI.Page
    {
        /// <summary>
        /// 申明一个全局变量：通过URL得到的选择的值
        /// </summary>
        public string m_selectedValue = string.Empty;
        protected void Page_Load(object sender, EventArgs e)
        {
            //注册ajaxpro
            AjaxPro.Utility.RegisterTypeForAjax(typeof(AjaxTest.DropDownListTest));
            //得到选择的值
            m_selectedValue = Request.QueryString["Temp"] == null ?
                string.Empty : Request.QueryString["Temp"].ToString();
            //注册onchange事件
            this.DropDownList1.Attributes.Add("onchange", "return _Onchange();");
            //注册刷新按钮的事件
            this.Button1.Attributes.Add("onclick","return test();");
        }
        /// <summary>
        /// 返回dataset值
        /// </summary>
        /// <param name="strSelectedValue">选择的值</param>
        /// <returns></returns>
        [AjaxPro.AjaxMethod]
        public DataSet GetDataSet(string strSelectedValue)
        {
            DataSet ds = new DataSet();
            ds.Tables.Add(GetDataTable(strSelectedValue));
            return ds;        }
        /// <summary>
        /// 返回Table
        /// </summary>
        /// <param name="strSelectedValue">选择的值</param>
        /// <returns></returns>
        private DataTable GetDataTable(string strSelectedValue)
        {
            DataTable tblData = new DataTable();
            tblData.Columns.Add("Text");
            tblData.Columns.Add("Value");
            //选择了1
            if (strSelectedValue == "1")
            {
                tblData.Rows.Add("Obsession", "Karen");
                tblData.Rows.Add("Vanished", "Robards");
            }
            else
            {
                tblData.Rows.Add("Magician: Apprentice", "Feist, Raymong E.");
                tblData.Rows.Add("Magician: Master", "Feist");
            }            return tblData;
        }                  }
}web.config:
<httpHandlers>

<add verb="POST,GET" path="ajaxpro/*.ashx" type="AjaxPro.AjaxHandlerFactory, AjaxPro.2"/>
</httpHandlers>
注意：别用ajaxpro 7.7.31.1_DLL.zip 这个版本。返回dataset有问题请用以前的版本：最好用6.10.6.2测试结果合符要求

还是不行，我把测试语句：alert("good");放在：
function test()
    {
        //源下拉框
        var srcDropdown = document.getElementById(" <%=DropDownList1.ClientID %>");
        //得到选择的值
        var selectevalue = srcDropdown.options[srcDropdown.options.selectedIndex].value;
        //
        if(selectevalue.length>0)
        {
            window.location.href = "DropDownListTest.aspx?Temp=" + selectevalue;

        }
        else{alert("请选择");}
        //
        return false;
    }
中的第一句前，执行，放在第二句后就不执行了它，为什么

就是
function test()
    {
alert("good");
        //源下拉框
        var srcDropdown = document.getElementById(" <%=DropDownList1.ClientID %>");
        //得到选择的值
        var selectevalue = srcDropdown.options[srcDropdown.options.selectedIndex].value;
        //
        if(selectevalue.length>0)
        {
            window.location.href = "DropDownListTest.aspx?Temp=" + selectevalue;

        }
        else{alert("请选择");}
        //
        return false;
    }
此时，单击按钮时弹出”good"，而下面时：function test()
    {         //源下拉框
        var srcDropdown = document.getElementById(" <%=DropDownList1.ClientID %>");
        //得到选择的值
        var selectevalue = srcDropdown.options[srcDropdown.options.selectedIndex].value;
        //
alert("good");
        if(selectevalue.length>0)
        {
            window.location.href = "DropDownListTest.aspx?Temp=" + selectevalue;

        }
        else{alert("请选择");}
        //
        return false;
    } 单击时不弹出“good"，不知为什么

我又测试了一下，发现在 Page_Load中m_selectedValue 的值始终为空，不知为什么

我把我的代码贴上吧：
aspx中是：
<head runat="server" >
    <title>利国实验小学考试成绩输入</title>
<script language="javascript" type="text/javascript">

function GetTeamList()
{
    var nianji=document.getElementById("nianjiDropDownList");

    _Default.TeamName(nianji.value,TeamCallBack);
    _Default.xuekeName(nianji.value,xuekeCallBack);

}
function TeamCallBack(response)
{
    if(response.value !=null)
   {
        var team=document.getElementById("banjiDropDownList");
        var dt=response.value;
        team.length=0;
        for(var i=0;i<dt.Rows.length;i++)
        {
            var team_text=dt.Rows[i]["class"];
            var team_value=dt.Rows[i]["class"];
            team.options.add(new Option(team_text,team_value));
        }

    }
}function xuekeCallBack(response)
{
    if(response.value !=null)
   {
        var team=document.getElementById("xuekeDropDownList");
        var dt=response.value;
        team.length=0;
        for(var i=0;i<dt.Rows.length;i++)
        {
            var team_text=dt.Rows[i]["学科"];
            var team_value=dt.Rows[i]["学科"];
            team.options.add(new Option(team_text,team_value));
                    }

    }
     getData();

}  function getData()
{
      var p=document.getElementById("xuekeDropDownList");
      var pindex = p.selectedIndex;
      var pValue = p.options[pindex].value;
      var pText  = p.options[pindex].text;
      document.getElementById("<%=xmlabel.ClientID%>").innerText=pText;
} function test()
    {

        //源下拉框
        var srcDropdown = document.getElementById(" <%=nianjiDropDownList.ClientID %>");
        //得到选择的值
        var selectevalue = srcDropdown.options[srcDropdown.options.selectedIndex].value;
        alert("good");
        //
        if(selectevalue.length>0)
        {
            window.location.href = "Default.aspx?Temp=" + selectevalue;

        }
        else{alert("请选择");}
        //
        return false;
    } //onload事件
    function _OnLoad(TempValue)
    {
        if(TempValue.length>0)
        {
            _GetValue(TempValue);
            //
            var srcDropdown = document.getElementById(" <%=nianjiDropDownList.ClientID %>");
            //
            for(var i=0;i <srcDropdown.options.length;i++)
            {
                if(TempValue == srcDropdown.options[i].value)
                {
                    srcDropdown.options[i].selected  = true;
                    break;
                }
            }

        }
    } </script>
</head>
<body  onload="_OnLoad(' <%=m_selectedValue%>');" onkeypress=" return Enter();" >
aspx.cx中是：    public string m_selectedValue = string.Empty;
    [AjaxPro.AjaxMethod]
    public DataTable TeamName(string systemselectname)
    {
        try
        {
            OleDbConnection oleDbConnection1 = new OleDbConnection(@"Jet OLEDB:Global Partial Bulk Ops=2;Jet OLEDB:Registry Path=;Jet OLEDB:Database Locking Mode=1;Data Source=""D:\liuhai\wangscore\studentscore.mdb"";Jet OLEDB:Engine Type=5;Provider=""Microsoft.Jet.OLEDB.4.0"";Jet OLEDB:System database=;Jet OLEDB:SFP=False;persist security info=False;Extended Properties=;Mode=Share Deny None;Jet OLEDB:Encrypt Database=False;Jet OLEDB:Create System Database=False;Jet OLEDB:Don't Copy Locale on Compact=False;Jet OLEDB:Compact Without Replica Repair=False;User ID=Admin;Jet OLEDB:Global Bulk Transactions=1");
            oleDbConnection1.Open();           // OleDbCommand OleDbCommand1 = new OleDbCommand("Select class from banji Where grade=" + systemselectname + " order by ID desc", oleDbConnection1);
           //cmdresults = OleDbCommand1.ExecuteNonQuery();
            OleDbDataAdapter sda = new OleDbDataAdapter("Select class from banji Where grade=" + systemselectname + " order by ID ", oleDbConnection1);            DataTable dt = new DataTable();
            //SqlDataAdapter sda = new SqlDataAdapter(cmd);
            sda.Fill(dt);
            oleDbConnection1.Close();
            return dt;        }
        catch
        {
            return null;
        }
    }
    [AjaxPro.AjaxMethod]
    public DataTable xuekeName(string systemselectname)
    {
        try
        {
            OleDbConnection oleDbConnection1 = new OleDbConnection(@"Jet OLEDB:Global Partial Bulk Ops=2;Jet OLEDB:Registry Path=;Jet OLEDB:Database Locking Mode=1;Data Source=""D:\liuhai\wangscore\studentscore.mdb"";Jet OLEDB:Engine Type=5;Provider=""Microsoft.Jet.OLEDB.4.0"";Jet OLEDB:System database=;Jet OLEDB:SFP=False;persist security info=False;Extended Properties=;Mode=Share Deny None;Jet OLEDB:Encrypt Database=False;Jet OLEDB:Create System Database=False;Jet OLEDB:Don't Copy Locale on Compact=False;Jet OLEDB:Compact Without Replica Repair=False;User ID=Admin;Jet OLEDB:Global Bulk Transactions=1");
            oleDbConnection1.Open();            OleDbDataAdapter sda = new OleDbDataAdapter("Select 学科 from xueke Where 年级=" + systemselectname + " order by ID ", oleDbConnection1);            DataTable dt = new DataTable();
            //SqlDataAdapter sda = new SqlDataAdapter(cmd);
            sda.Fill(dt);
            oleDbConnection1.Close();
            return dt;        }
        catch
        {
            return null;
        }
    }
    protected void Page_Load(object sender, EventArgs e)
    {
        AjaxPro.Utility.RegisterTypeForAjax(typeof(_Default));
        m_selectedValue = Request.QueryString["Temp"] == null ?
            string.Empty : Request.QueryString["Temp"].ToString();        Label2.Text = m_selectedValue+"945";
        GridView1.Columns[1].HeaderText = ((HtmlInputHidden)((System.Web.UI.Page)System.Web.HttpContext.Current.Handler).FindControl("xmlabel")).Value.ToString();
             GridView1.AutoGenerateColumns = false;


        if (!IsPostBack)
        {
       banjiDropDownList.DataSource = TeamName(nianjiDropDownList.SelectedItem.Value.Trim());
       banjiDropDownList.DataTextField = "class";
       banjiDropDownList.DataValueField = "class";
       banjiDropDownList.DataBind();       xuekeDropDownList.DataSource = xuekeName(nianjiDropDownList.SelectedItem.Value.Trim());
       xuekeDropDownList.DataTextField = "学科";
       xuekeDropDownList.DataValueField = "学科";
       xuekeDropDownList.DataBind();
       this.nianjiDropDownList.Attributes.Add("onclick", "GetTeamList();");
            this.xuekeDropDownList.Attributes.Add("onclick", "getData()");
            this.xianshishengButton.Attributes.Add("onclick","return test();");
                       this.baocunButton.Attributes.Add("onclick", "return   _confirm();");
            }

    }

调试易

ajaxpro两级联动出现错误

解决方案 »