Question

ASP.NET动态创建DropDownList，的SelectedIndexChange事件触发后，连原先的DropDownList都消失掉

我通过后台动态创建了个DropDownList，但添加了个SelectedIndexChange事件，然后，把AutoPostBack设置为true，当，我改变DropDownList选项的时候，DropDownList消失掉了.。我的源码： public partial class _Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { DropDownList ddlControl = new DropDownList(); ddlControl.ID = "ddlEx"; ddlControl.AutoPostBack = true; ddlControl.SelectedIndexChanged += new EventHandler(ddlEx_SelectedIndexChanged); ddlControl.Items.Insert(0, new ListItem("Please choose", "-1")); ddlControl.Items.Insert(1, new ListItem("Please choose1", "0")); ddlControl.Visible = true; pan.Controls.Add(ddlControl); } } protected void ddlEx_SelectedIndexChanged(object sender, EventArgs e) { TextBox tbxControl = new TextBox(); tbxControl.ID = "tbxEx"; } }

Answer 1

把if(!IsPostBack)去掉 不要判断。