【精华】如何让ascx里2个DroDdownList联动起来？100分+

经测试，下面这样OK：
public class WebUserControl1 : System.Web.UI.UserControl
{
protected System.Web.UI.WebControls.DropDownList dd1;
protected System.Web.UI.WebControls.DropDownList dd2; private void Page_Load(object sender, System.EventArgs e)
{
dd1.AutoPostBack = true;
}
override protected void OnInit(EventArgs e)
{
InitializeComponent();
base.OnInit(e);
}
private void InitializeComponent()
{
this.dd1.SelectedIndexChanged += new System.EventHandler(this.dd1_SelectedIndexChanged);
this.Load += new System.EventHandler(this.Page_Load);
}
private void dd1_SelectedIndexChanged(object sender, System.EventArgs e)
{
Response.Write("<script>alert('1')<script>;");//这里改写成绑定dd2
}
}
然后使用Control c = Page.LoadControl("WebUserControl1 ");
this.main.Controls.Add(c); 测试时main是在form中的panel

举个例子吧,在控件里写就是了，和页面没有任何关系的。
private void DrplstCityBind()
{
int provinceID=Convert.ToInt32(drplstProvince.SelectedItem.Value);
drplstCity.DataSource=City.ListCity(provinceID);
drplstCity.DataTextField="Name";
drplstCity.DataValueField="ID";
drplstCity.DataBind();
drplstCity.Items.Insert(0,new ListItem("-- Select --","0"));
}
private void drplstProvince_SelectedIndexChanged(object sender, System.EventArgs e)
{
DrplstCityBind();
}
记得把第一个dropdownlist（在本例中是drplstProvince）的AutoPostBack属性设为1

erwanfan(teddyxiong)
我用的是VS2005
自定义控件是按钮选着添加的。
你的方法会让页面刷新为初试状态，就没有B.ascx控件了。

1.aspx的初试状态是没加载控件的。
点击按钮后用
Control c = Page.LoadControl("WebUserControl1 ");
this.main.Controls.Add(c);
的方法加载用户自定义控件。
然后在使用用户自定义控件里的 dropdownlist。

dd1.AutoPostBack = true;
只要开启AutoPostBack属性就会刷新页面就会回到没加载控件时的状态。

把Control c = Page.LoadControl("WebUserControl1 ");
this.main.Controls.Add(c);
放到if(!IsPostBack){}之外，每次post就加载一边就行了。

我就是放那外面的呀。不行呀。能不能QQ？让你QQ看

1.aspx
<form>
<div>
<asp:LinkButton ID="h07" runat="server"OnClick="h07_Click">A</asp:LinkButton>
</div>
        <div >
            <asp:PlaceHolder ID="main" runat="server"></asp:PlaceHolder>
        </div>
</div>
</form>
1.cs
    protected void h07_Click(object sender, EventArgs e)
    {
        this.main.Dispose();
        Control c = Page.LoadControl(good.Login("../A.ascx"));
        this.main.Controls.Add(c);
    }
A.ascx
<asp:DropDownList ID="h02ddl1" runat="server" ></asp:DropDownList>D1
<asp:DropDownList ID="h02ddl2" runat="server" ></asp:DropDownList>D2加载A.ascx时会LOAD里给D1 D2 加数据。
在1.aspx里如何使用联动？

a.ascx和你要加载该用户控件的窗体是无关的.
你只要在a.ascx中实现联动就可以了.

这样不行，改变DroDdownList选择项后，会postback，由于之前加载的服务段控件A.ascx是动态加载的，后台服务器重新响应请求时，没有重新运行
this.main.Dispose();
Control c = Page.LoadControl(good.Login("../A.ascx"));
this.main.Controls.Add(c);
这时后台没有A.ascx控件对象，更没有A.ascx里的DroDdownList控件，所以不会执行DroDdownList的SelectedIndexChanged

解决办法：
前台<input id="booloadctrl" type="hidden" runat=server>
<asp:LinkButton ID="h07" runat="server">/asp:LinkButton>
后台声明对应于前台booloadctrl的控件protected System.Web.UI.HtmlControls.HtmlInputHidden booloadctrl;
在PageLoad的if(!IsPostBack){}块之外加
h07.Attributes["onclick"] = "document.all.booloadctrl.value='true'";
if(booloadctrl.Value== "true")
{
   this.main.Dispose();
   Control c = Page.LoadControl(good.Login("../A.ascx"));
   this.main.Controls.Add(c);
}
去掉原有h07_Click，以及隐藏代码中的给h07绑定click事件的代码。

因为是动态控件，所以要响应他的事件，肯定是需要每次都重新load的
上面的办法是用hidden控件记录是否要load自定义控件，通过点击LinkButton调用javascript给hidden控件赋值为true，后台page_load的时候判断hidden值，为true则动态加载控件。

<input id="booloadctrl" type="hidden" runat=server>
<asp:LinkButton ID="h07" runat="server">/asp:LinkButton>
<asp:LinkButton ID="h08" runat="server">/asp:LinkButton>
在PageLoad的if(!IsPostBack){}块之外加
h07.Attributes["onclick"] = "document.all.booloadctrl.value=h07.id";if(booloadctrl.Value== "h07")
{
this.main.Dispose();
Control c = Page.LoadControl(good.Login("../A.ascx"));
this.main.Controls.Add(c);
}
if(booloadctrl.Value== "h08")
{
this.main.Dispose();
Control c = Page.LoadControl(good.Login("../A.ascx"));
this.main.Controls.Add(c);
}问题：在07 08 之间如何切换改边booloadctrl.Value的值？？这是个问题吧

runat="server" 下onclick好象无效

不用都不行了。没别的办法。
erwanfan(teddyxiong) 的办法还是有问题。
因为点击按钮后又会从新加载一次原样的ASCX。
还是没解决问题。算了。
还是的综合应用。

晚上没人有办法解决分就给erwanfan(teddyxiong)做辛苦费了

http://www.cnblogs.com/xucanzhao/archive/2005/09/28/246163.html
Any problem,send me email.

经过测试对于runat="server"的LinkButton即使后台没有它绑定事件（LinkButton需已声明），点击后，还是会postback的，不过只执行了Page_Load而已。多个控件的情况也可以想办法，比如如果有07 08 两个控件，booloadctrl.Value的值设为“07，08”，后台根据之load多个控件。虽然控件每次在Page_Load重新加载，但是前台页面是有他的信息和状态的，所以当它重新加载后系统还是会根据前台post过来的状态初始化它，所以即使控件是重新load，DropDownList的SelectedIndexChanged还可以触发,SelectedIndex等还可以获得。所以如果第一个DropDownList的所有下拉选项不会因为每次重新load而发身变化的话，就可以像前面我说的那样应用，而第二个DropDownList反正它每次都是在SelectedIndexChanged中绑定的，就更没有问题。其实就是因为是点击按钮动态加载用户自定义的二级联动控件（后台代码中没有它的全局定义），所以才需要每次都重新load。只要是动态加载，即使用Ajax，仍然是需要每次都重新加载的。

public class WebUserControl1 : System.Web.UI.UserControl
{
protected System.Web.UI.WebControls.DropDownList dd1;
protected System.Web.UI.WebControls.DropDownList dd2;private void Page_Load(object sender, System.EventArgs e)
{
dd1.AutoPostBack = true;
}
override protected void OnInit(EventArgs e)
{
InitializeComponent();
base.OnInit(e);
}
private void InitializeComponent()
{
this.dd1.SelectedIndexChanged += new System.EventHandler(this.dd1_SelectedIndexChanged);
this.Load += new System.EventHandler(this.Page_Load);
}
private void dd1_SelectedIndexChanged(object sender, System.EventArgs e)
{
Response.Write("<script>alert('1')<script>;");//这里改写成绑定dd2
}
}
然后使用Control c = Page.LoadControl("WebUserControl1 ");
this.main.Controls.Add(c); 测试时main是在form中的panel

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;namespace TestExam
{
/// <summary>
/// TestFxuan 的摘要说明。
/// </summary>
public class TestFxuan : System.Web.UI.Page
{
protected System.Web.UI.WebControls.Label Label1;
protected System.Web.UI.WebControls.CheckBoxList CheckBoxList1;
protected System.Web.UI.WebControls.RadioButtonList RadioButtonList1;

private void Page_Load(object sender, System.EventArgs e)
{
// 在此处放置用户代码以初始化页面
if(!this.IsPostBack)
{
this.RblToBind();
this.CblToBind();
}
}
private void RblToBind()
{
SqlConnection con=DB.CreateConn();
con.Open();
string SqlSet="select cTitle, cA,cB,cC,cD from Control";
SqlDataAdapter sdr=new SqlDataAdapter(SqlSet,con);
DataSet ds=new DataSet();
sdr.Fill(ds,"Control");
this.RadioButtonList1.Items.Add(ds.Tables["Control"].Rows[0][1].ToString());
            this.RadioButtonList1.Items.Add(ds.Tables["Control"].Rows[0][2].ToString());
this.RadioButtonList1.Items.Add(ds.Tables["Control"].Rows[0][3].ToString());
this.RadioButtonList1.Items.Add(ds.Tables["Control"].Rows[0][4].ToString());
this.Label1.Text=ds.Tables["Control"].Rows[0][0].ToString(); this.RadioButtonList1.RepeatDirection=System.Web.UI.WebControls.RepeatDirection.Horizontal;
this.RadioButtonList1.RepeatColumns=1;
con.Close();
}
private void CblToBind()
{
SqlConnection con=DB.CreateConn();
con.Open();
string SqlSet="select cTitle, cA,cB,cC,cD from Control";
SqlDataAdapter sdr=new SqlDataAdapter(SqlSet,con);
DataSet ds=new DataSet();
sdr.Fill(ds,"Control");
this.CheckBoxList1.Items.Add(ds.Tables["Control"].Rows[0][1].ToString());
this.CheckBoxList1.Items.Add(ds.Tables["Control"].Rows[0][2].ToString());
this.CheckBoxList1.Items.Add(ds.Tables["Control"].Rows[0][3].ToString());
this.CheckBoxList1.Items.Add(ds.Tables["Control"].Rows[0][4].ToString());
this.CheckBoxList1.RepeatDirection=System.Web.UI.WebControls.RepeatDirection.Horizontal;
this.CheckBoxList1.DataBind();
con.Close();
}

#region Web 窗体设计器生成的代码
override protected void OnInit(EventArgs e)
{
//
// CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
//
InitializeComponent();
base.OnInit(e);
}

/// <summary>
/// 设计器支持所需的方法 - 不要使用代码编辑器修改
/// 此方法的内容。
/// </summary>
private void InitializeComponent()
{
this.Load += new System.EventHandler(this.Page_Load); }
#endregion
}
}
然后将主控件的AUTO什么属性设置为TRUE。。

我也来一断
using System;
using System.Data;
using System.Web.UI;
using System.Web.UI.WebControls;namespace AjaxSampleCS.Sample1
{
  public class DropDownLink : Page
  {
    protected DropDownList countries;
    protected DropDownList states;
    protected Button submit;    private void Page_Load(object sender, EventArgs e)
    {

      //Make methods ed with the AjaxMethod attribute of this class
      //available to client-side calls.
      Ajax.Utility.RegisterTypeForAjax(typeof(DropDownLink));
      if (!Page.IsPostBack)
      {
        countries.DataSource = DAL.GetShippingCountries();
        countries.DataTextField = "Country";
        countries.DataValueField = "Id";
        countries.DataBind();        countries.Items.Insert(0, new ListItem("Please Select", "0"));
      }
    }    [Ajax.AjaxMethod()]
    public DataView GetStates(int countryId)
    {
      return DAL.GetCountryStates(countryId);
    }    private void submit_Click(object sender, EventArgs e)
    {      //Rember that the states dropdown was populate client-side
      //that means it's values aren't preserved in the viewstate
      //the only way to get the selected value is the tried and tested Request.Form
      string selectedStateId = Request.Form[states.UniqueID];
      Response.Write("You selected province/state id: " + selectedStateId);      //this also means that if we want to redisplay the form with the user's selected value,
      //we need to do some extra work      //should do some user validation...
      states.DataSource = DAL.GetCountryStates(Convert.ToInt32(countries.SelectedIndex));
      states.DataTextField = "State";
      states.DataValueField = "Id";
      states.DataBind();
      states.SelectedIndex = states.Items.IndexOf(states.Items.FindByValue(selectedStateId));    }    #region Web Form Designer generated code
    protected override void OnInit(EventArgs e)
    {
      //
      // CODEGEN: This call is required by the ASP.NET Web Form Designer.
      //
      InitializeComponent();
      base.OnInit(e);
    }
    /// <summary>
    /// Required method for Designer support - do not modify
    /// the contents of this method with the code editor.
    /// </summary>
    private void InitializeComponent()
    {
      this.submit.Click += new EventHandler(this.submit_Click);
      this.Load += new EventHandler(this.Page_Load);
    }
    #endregion  }
}
  public static DataView GetCountryStates(int countryId)
  {
      DataSet allData = GetShippingData();
      DataView statesView = allData.Tables["states"].DefaultView;
      statesView.RowFilter = "CountryId = " + countryId.ToString();
      return statesView;
  }
前台<script language="javascript">
//states dropdown
var statesList = document.getElementById("<%=states.ClientID%>");//called by the onChange javascript event on the dropdown
function LoadStates(countries)
{
  var countryId = countries.options[countries.selectedIndex].value;
  if (countryId > 0)
  {
    //DropDownLink is defined by Ajax.Net because that's the name of the type we registered
    DropDownLink.GetStates(countryId, LoadStates_CallBack);
  }
  else
  {
    //clear the states dropdown
    states.options.length = 0;
  }
}
//callback we told Ajax.Net to pass the response tos
function LoadStates_CallBack(response)
{
  //if the server side code threw an exception
  if (response.error != null)
  {
    alert(response.error); //we should probably do better than this
    return;
  }


  var states = response.value;
  //if the response wasn't what we expected
  if (states == null || typeof(states) != "object")
  {
    return;
  }

  statesList.options.length = 0; //reset the states dropdown
  //note that this is JavaScript casing and the L in length is lowercase for arrays
  for (var i = 0; i < states.Rows.length; ++i)
  {
    statesList.options[statesList.options.length] = new Option(states.Rows[i].State, states.Rows[i].Id);
  }
}
</script>

最后我用的是JS解决。把内容都放到JS里面做个数组进行选择。
怎么好多人都没看贴的题目就发贴。
AJAX吧。还是解决好多问题比较容易点。可能习惯了。

调试易

【精华】如何让ascx里2个DroDdownList联动起来？100分+

解决方案 »