多个DropDownList的SelectedIndexChanged 问题 急急急

Question

有三个dropdownlist 都是可回发的
第一个DropDownList1_SelectedIndexChanged后会过滤绑定DropDownList2的内容，
但我点击DropDownList2时　为什么又执行了一遍DropDownList1_SelectedIndexChanged然后才执行DropDownList２_SelectedIndexChanged　我点DropDownList2就应执行DropDownList2_SelectedIndexChanged
为什么还要执行DropDownList1_SelectedIndexChanged请问如何才能让点DropDownList2不执行DropDownList1_SelectedIndexChanged

Answer 1

给DropDownList1绑定数据的方法要写在protected void Page_Load(...)
if(!Page.IsPostBack)
{
  //这里
}btw:楼主你真是"文不加点"啊

Answer 2

你最好把你要调用的事件,或者你写在Page_load事件中的代码放在
if(!IsPostBack)
{
   //here
}要不然,不仅仅是你点击AutoPostBack属性为true的DropDownList时会重新执行一遍.你单击任何一个按钮也要执行,只要回发到服务器的都要执行.
这样的问题问的太多了.

Answer 3

除了
    protected void Page_Load(object sender, EventArgs e)
    {
        if (IsPostBack) return;
        InitData();//第一次请求时绑定初始化的数据,
    }之外你的问题的第一句话就是答案

Answer 4

同意，web程序和windows程序，这点上区别很大。IsPostBack是关键。

Answer 5

我是写在isPostBack里了，对了我所有的DropDownList都放在一个</asp:UpdatePanel>里了
现在问题就是当我选一下BindDropDownList1它回发后执行DropDownList1_SelectedIndexChanged
当我选一下DropDownList2它回发后还要执行一下DropDownList1_SelectedIndexChanged,然后又执行DropDownList２_SelectedIndexChanged
选DropDownList２后应只执行DropDownList2_SelectedIndexChanged啊，请问为什么，如何解决
protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            BindDropDownList1();
            BindDropDownList2();
            BindDropDownList3();
        }    }    protected void DropDownList2_SelectedIndexChanged(object sender, EventArgs e)
    {
        DropDownList dropDownList = sender as DropDownList;
        if (dropDownList.ID == "DropDownList2")
        {
            BindDropDownList3();
        }
    }    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        DropDownList dropDownList = sender as DropDownList;
        if (dropDownList.ID == "DropDownList1")
        {
            BindDropDownList2();
            BindDropDownList3();
        }
        
    }//代码都不用看意思就是绑定第1个DropDownList
    private void BindDropDownList1()
    {
        Dictionary<String, String> hashtable = new Dictionary<string, string>();
        hashtable.Add("0", "＝选择分类＝");
        hashtable.Add("1", "AAA");
        hashtable.Add("2", "BBB");
        hashtable.Add("3", "CCC");        DropDownList1.DataSource = hashtable;
        DropDownList1.DataTextField = "value";
        DropDownList1.DataValueField = "key";
        DropDownList1.DataBind();
    
    }//代码都不用看意思就是绑定第2个DropDownList
    private void BindDropDownList2()
    {
        String tableName = DropDownList1.SelectedValue; 
        String sqlString = "";        if (tableName == "0")
        {
            Dictionary<String, String> hashtable = new Dictionary<string, string>();
            hashtable.Add("0", "＝全部＝");            DropDownList2.DataSource = hashtable;
            DropDownList2.DataTextField = "value";
            DropDownList2.DataValueField = "key";
            DropDownList2.DataBind();
        }        if (tableName == "1")
        {
            sqlString = "***********************";            DataTable dt = _boBase.GetDataTable(sqlString);
            DropDownList2.DataSource = dt;
            DropDownList2.DataTextField = "AAA";
            DropDownList2.DataValueField = "ID";
            DropDownList2.DataBind();            ListItem listItem = new ListItem();
            listItem.Value = "0";
            listItem.Text = "＝全部＝";
            DropDownList2.Items.Insert(0, listItem);
        }
       
        
    }
//就是绑定第３个DropDownList
    private void BindDropDownList3()
    { 
        String tableName = DropDownList1.SelectedValue; 
        String sqlString = "";
        
        if (tableName == "0")
        {
                Dictionary<String, String> hashtable = new Dictionary<string, string>();
                hashtable.Add("0", "＝全部＝");                DropDownList3.DataSource = hashtable;
                DropDownList3.DataTextField = "value";
                DropDownList3.DataValueField = "key";
                DropDownList3.DataBind();
            
        }
        if (tableName == "1")
        {
            String drpSelect = DropDownList2.SelectedValue;            if (drpSelect == "0")
            {
                Dictionary<String, String> hashtable = new Dictionary<string, string>();
                hashtable.Add("0", "＝全部＝");                DropDownList3.DataSource = hashtable;
                DropDownList3.DataTextField = "value";
                DropDownList3.DataValueField = "key";
                DropDownList3.DataBind();
            
            }
       
    }

Answer 6

有这样的多选择，一定记得要通过判断是否页面是否回传过来的。
if(!Page.IsPostBack)
{}

Answer 7

因为回传时刷新了页面，刷新后DropDownList1重新加载自己的列表项，所以DropDownList1_SelectedIndexChanged事件又被触发。

Answer 8

 if (!IsPostBack)
        {
            //绑定出激活的管理站，下的干支渠
            DAL.T_WaterBalanceDSTableAdapters.ganz_tabTableAdapter adp = new DAL.T_WaterBalanceDSTableAdapters.ganz_tabTableAdapter();
            this.ddlganzname.DataSource = adp.GetDataGanzName();
            this.ddlganzname.DataTextField = "ganz_mic";
            this.ddlganzname.DataValueField = "ganz_bih";
            this.ddlganzname.DataBind();
        }
 protected void ddlganzname_SelectedIndexChanged(object sender, EventArgs e)
    {
        this.ddlduanmane.Items.Clear();
        this.ddlduanmane.Items.Add("全部");
        DAL.T_WaterBalanceDSTableAdapters.duan_tabTableAdapter adp = new DAL.T_WaterBalanceDSTableAdapters.duan_tabTableAdapter();
        this.ddlduanmane.DataSource = adp.GetDataDuanName(this.ddlganzname.SelectedValue);
        this.ddlduanmane.DataTextField = "duan_mic";
        this.ddlduanmane.DataValueField = "duan_bih";
        this.ddlduanmane.DataBind();
    }
    protected void ddlduanmane_SelectedIndexChanged(object sender, EventArgs e)
    {
        this.ddldouname.Items.Clear();
        this.ddldouname.Items.Add("全部");
        DAL.T_WaterBalanceDSTableAdapters.douq_tabTableAdapter adp = new DAL.T_WaterBalanceDSTableAdapters.douq_tabTableAdapter();
        this.ddldouname.DataSource = adp.GetDataDouqName(this.ddlduanmane.SelectedValue);
        this.ddldouname.DataTextField = "douq_mic";
        this.ddldouname.DataValueField = "douq_bih";
        this.ddldouname.DataBind();
    }
    protected void ddlxangname_SelectedIndexChanged(object sender, EventArgs e)
    {
        this.ddlcunname.Items.Clear();
        this.ddlcunname.Items.Add("全部");
        DAL.T_WaterBalanceDSTableAdapters.cunz_tabTableAdapter adp = new DAL.T_WaterBalanceDSTableAdapters.cunz_tabTableAdapter();
        this.ddlcunname.DataSource = adp.GetDataCunName(this.ddlxangname.SelectedValue);
        this.ddlcunname.DataTextField = "cunz_mic";
        this.ddlcunname.DataValueField = "cunz_bih";
        this.ddlcunname.DataBind();
    }
    protected void ddlcunname_SelectedIndexChanged(object sender, EventArgs e)
    {
        this.ddlzuname.Items.Clear();
        this.ddlzuname.Items.Add("全部");
        DAL.T_WaterBalanceDSTableAdapters.zubi_tabTableAdapter adp = new DAL.T_WaterBalanceDSTableAdapters.zubi_tabTableAdapter();
        this.ddlzuname.DataSource = adp.GetDataZuname(this.ddlcunname.SelectedValue);
        this.ddlzuname.DataTextField = "zubi_mic";
        this.ddlzuname.DataValueField = "zubi_bih";
        this.ddlzuname.DataBind();
    }
    protected void ddlguanjiyear_SelectedIndexChanged(object sender, EventArgs e)
    {        //在这里 SelectedIndex =0 会把"---"这个作为参数 来查询灌季名称，会提示"---"无法转换成int行，  ---为字符窜，
        
        if (ddlguanjiyear.SelectedIndex > 0)
        {
            this.ddlguanjiname.Items.Clear();
            this.ddlguanjiname.Items.Add("全部");
            DAL.T_WaterBalanceDSTableAdapters.guaj_tabTableAdapter adp = new DAL.T_WaterBalanceDSTableAdapters.guaj_tabTableAdapter();
            this.ddlguanjiname.DataSource = adp.GetDatayearName(this.ddlguanjiyear.SelectedValue);
            this.ddlguanjiname.DataTextField = "guaj_mic";
            this.ddlguanjiname.DataValueField = "guaj_mic";
            this.ddlguanjiname.DataBind();
        }
    }
举个例子

Answer 9

每个DropDownList放在不同的UpdatePanel里试试

Answer 10

嗯,应该不用放几个UpdatePanel的.我做了试验了你检查一下DropDownList1的EnableViewState属性是不是true,要设置成true

Answer 11

To 风中聆听
设成true了，还是没解决问题