Question

在我的网络应用程序中，当我选择一个给出错误的下拉控件时。无法在DropDownList中选择多个项目。这是我的代码......

    try
    {             
        ddlState.Items.Clear();
        ddlState.Enabled = true;
        ListItem li1 = new ListItem();
        li1.Value = "0";
        li1.Text = "Select State";
        ddlState.Items.Add(li1);
        clsStates.Countryid = int.Parse(ddlCountry.SelectedValue.ToString());
        DataSet ds = clsStates.selectStateBl();
        for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
        {
            li1 = new ListItem();
            li1.Text = ds.Tables[0].Rows[i]["statename"].ToString();
            li1.Value = ds.Tables[0].Rows[i]["stateid"].ToString();
            ddlState.DataTextField = "statename";
            ddlState.DataValueField = "stateid";
            ddlState.Items.Add(li1);
        }
    }
    catch
    {

    }

这是对国家代码的约束......

     try
    {

        ListItem li = new ListItem();

        DataSet ds = clsCountrys.selectCountryB();

        for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
        {
            li = new ListItem();
            li.Text = ds.Tables[0].Rows[i]["countryname"].ToString();
            li.Value = ds.Tables[0].Rows[i]["countryid"].ToString();
            if (li.Value == Session["usercountry"].ToString())
                li.Selected = true;
            ddlCountry.DataTextField = "countryname";
            ddlCountry.DataValueField = "countryid";
            ddlCountry.Items.Add(li);
        }
    }
    catch
    {

    }

这是状态绑定到下拉控件..

     try
    {
        ddlState.Items.Clear();
        ddlState.Enabled = true;
        ddlState.ClearSelection();
        ListItem li1 = new ListItem();
        li1.Value = "0";
        li1.Text = "Select State";
        ddlState.Items.Add(li1);
        clsStates.Countryid = int.Parse(ddlCountry.SelectedValue.ToString());
        DataSet ds = clsStates.selectStateBl();
        for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
        {

            li1 = new ListItem();
            li1.Text = ds.Tables[0].Rows[i]["statename"].ToString();
            li1.Value = ds.Tables[0].Rows[i]["stateid"].ToString();
            if (Session["userstate"].ToString() == li1.Value)
                li1.Selected = true;
            ddlState.DataTextField = "statename";
            ddlState.DataValueField = "stateid";
            ddlState.Items.Add(li1);
        }
    }
    catch
    {

    }

Answer 1

使用ddlState.ClearSelection()方法清除默认选择。

查看此帖子：ASP.NET Tips: DropDownList.ClearSelection() to avoid "Cannot have multiple items selected in DropDownList"

修改

try { ddlState.ClearSelection(); ddlState.Items.Clear(); ddlState.Enabled = true; ListItem li1 = new ListItem(); li1.Value = "0"; li1.Text = "Select State"; ddlState.Items.Add(li1); clsStates.Countryid = int.Parse(ddlCountry.SelectedValue.ToString()); DataSet ds = clsStates.selectStateBl(); for (int i = 0; i < ds.Tables[0].Rows.Count; i++) { li1 = new ListItem(); li1.Text = ds.Tables[0].Rows[i]["statename"].ToString(); li1.Value = ds.Tables[0].Rows[i]["stateid"].ToString(); ddlState.DataTextField = "statename"; ddlState.DataValueField = "stateid"; ddlState.Items.Add(li1); } //code updated by pranay rana ddlState.ClearSelection(); ListItem li = ddlState.Items.FindByValue(Session["userstate"].ToString()); if (li != null) { li.Selected = true; } //code updated by pranay rana } catch { }

在下拉控件中获取错误selectedindexchanged事件？

1 个答案: