动态生成的DropDownList控件，为什么不响应事件？

[MasterLRC]

我想实现：
点击一个按钮，则自动在 TABLE中 加入一行，生成并加入一个 DropDownList 控件

要对 DropDownList 控件的SelectedIndexChanged 事件响应。



我对思归大哥的程序作了如下添加：

int Count
{
get
{
object o = ViewState["Count"];
if(o==null)
return 0;
return (int)ViewState["Count"];
}
set
{
ViewState["Count"] = value;
}
}
DropDownList AddDDL()
{
TableRow tr = new TableRow();
TableCell tc = new TableCell();

DropDownList ddl = new DropDownList();
<<<<<<<以下这三行是我加的
ddl.Items.Add(new ListItem("1","1"));
ddl.Items.Add(new ListItem("2","2"));
ddl.SelectedIndexChanged +=new EventHandler(ddl_SelectedIndexChanged);
tc.Controls.Add(ddl);
tr.Cells.Add(tc);
myTab.Rows.Add(tr);

return ddl;
}

protected void ddl_SelectedIndexChanged(Object o ,EventArgs e)
{
Response.Write("OK");
}

void PopulateDLL(DropDownList ddl)
{
for(int i = 0; i < Count; i++)
{
AddDDL();
}
}

protected void Add(Object sender,EventArgs e)
{
DropDownList ddl = AddDDL();
PopulateDLL(ddl);
Count++;
}


请参考

http://expert.csdn.net/Expert/topic/2229/2229874.xml?temp=.7068903

[MasterLRC]

生成控件是没有总是了

可是当我改 下拉列表框时却不触发事件。

在调试时我发现执行

ddl.SelectedIndexChanged +=new EventHandler(ddl_SelectedIndexChanged);

ddl.SelectedIndexChanged 的值提示为：

ddl.SelectedIndexChanged 错误: 标识符“ddl”超出范围

[MasterLRC]

大家帮忙呀，小弟实在是没法了！

[slinfo]

1.在InitializeComponent()里面写上
this.DropDownList1.SelectedIndexChanged += new System.EventHandler(this.DropDownList1_SelectedIndexChanged);

2.然后在
private void DropDownList1_SelectedIndexChanged(object sender, System.EventArgs e)
{
}
里面写你需要实现的代码

希望对你有用

[lemong]

void PopulateDLL(DropDownList ddl)
{
for(int i = 0; i < Count; i++)
{
AddDDL();
}
}

其中的参数没有用到

protected void Add(Object sender,EventArgs e)
{
DropDownList ddl = AddDDL();
PopulateDLL(ddl);
Count++;
}
这一段的实际作用好像添加了很多相同id的控件，而且作用范围在同一个范围之内

问题不少阿

[lemong]

protected void Add(Object sender,EventArgs e)
{
DropDownList ddl = AddDDL();
PopulateDLL(ddl);
Count++;
}
这一段的实际作用好像添加了很多相同id的控件，而且作用范围在同一个范围之内

对不起，应该是至少两个了

[chnking]

不行的,在按钮点击事件中给控件的事件挂钩是不起作用的,这些事要在page_load事件中或之前做的

[saucer]

when you recreate the DropDownLists, you shouldn't add the Items again, if you look at my original code, you will know, the control is only populated inside Add method

[MasterLRC]

动态生成控件的代码是大牛“思归”写的，我试过了，没问题！

想ID不同只要在

DropDownList ddl = new DropDownList();
后面给一个唯一的ID就行了。

[saucer]

<form runat=server id=form1>
<asp:Table id=tbl runat=server />
<asp:Button id=btn runat=server text=add Onclick="Add" />
<asp:Button id=btn2 runat=server text=submit/>
</form>

<script language=C# runat=server>
int Count
{
get
{
object o = ViewState["Count"];
if (o==null)
return 0;
return (int)ViewState["Count"];
}
set
{
ViewState["Count"] = value;
}
}

DropDownList AddDDL(int index)
{
TableRow tr = new TableRow();
TableCell tc = new TableCell();

DropDownList ddl = new DropDownList();
ddl.ID = "DDL" + index.ToString();
//ddl.AutoPostBack= true;
ddl.SelectedIndexChanged += new EventHandler(DDL_Changed);
tc.Controls.Add(ddl);
tr.Cells.Add(tc);
tbl.Rows.Add(tr);

return ddl;
}

void PopulateDLL(DropDownList ddl)
{
for (int i=1; i <=10; i++)
ddl.Items.Add(i.ToString());
}


void Page_Load(Object sender, EventArgs e)
{
for (int i=0; i < Count; i++)
{
AddDDL(i);
}
}

void Add(Object sender, EventArgs e)
{
DropDownList ddl= AddDDL(Count);

PopulateDLL(ddl);
Count++;
}

void DDL_Changed(Object sender, EventArgs e)
{
DropDownList ddl= (DropDownList)sender;
Response.Write(String.Format("{0} is changed to {1}<BR>", ddl.ID, ddl.SelectedItem.Value));
}
</script>

[MasterLRC]

那么，能让这些DropDownList响应SelectedIndexChange事件吗？

[MasterLRC]

试ing

[MasterLRC]

哇哈！成了！