以程序方式正确引用ASP占位符

Question

我有下面的代码，它按预期工作；选择单选按钮时，我希望CheckChanged事件将控件添加到StatusBar占位符。如何从事件中引用此控件？如有任何反馈，我们将不胜感激。

    public void Page_Load(object sender, EventArgs e)
    {
            for (int T = 0; T <= 26; T++)
            {
                Label x = new Label();
                x.ID = T.ToString();
                x.Text = "orem ipsum dolor sit amet, consectetur adipiscing elit. Nulla blandit id felis ac volutpat. Aenean tempor faucibus est, ac feugiat libero egestas sit amet. Aliquam";
                Label y = new Label();
                y.ID = "Title_" + T.ToString();
                y.Text = "Title " + T.ToString();

                RadioButton Radio1 = new RadioButton();
                Radio1.ID = "R_" + T.ToString();
                Radio1.Text = "Yes";
                Radio1.GroupName = "Radio_" + T.ToString();
                Radio1.CheckedChanged += new EventHandler(this.CheckedChanged);
                Radio1.AutoPostBack = true;
                RadioButton Radio2 = new RadioButton();
                Radio2.ID = "RX_" + T.ToString();
                Radio2.Text = "No";
                Radio2.GroupName = "Radio_" + T.ToString();
                Radio2.CheckedChanged += new EventHandler(this.CheckedChanged);
                Radio2.AutoPostBack = true;
                PlaceHolder StatusBar = new PlaceHolder();
                StatusBar.ID = "status_" + T.ToString();

                PlaceHolder pcl = new PlaceHolder();
                pcl.ID = "test_" + T.ToString();
                pcl.Controls.Add(y);
                pcl.Controls.Add(new LiteralControl("<br>"));
                pcl.Controls.Add(x);
                pcl.Controls.Add(new LiteralControl("<br>"));
                pcl.Controls.Add(Radio1);
                pcl.Controls.Add(Radio2);
                pcl.Controls.Add(new LiteralControl("<br><br>"));
                form1.Controls.Add(pcl);
                form1.Controls.Add(StatusBar);
            }
        }

    protected void CheckedChanged(object sender, EventArgs e)
    {
        RadioButton tRadio = (RadioButton)sender;
        if (tRadio.Text == "Yes")
        {
            Statusbar.Controls.Add(somecontrol);
        }

    }

Answer 1

您应该使用FindControl来查找StatusBar控件。如果您将StatusBar的类型从PlaceHolder更改为`Panel，您的问题就会得到解决。

更新：您不需要使用Panel控件来代替PlaceHolder，但PlaceHolder生成标记，这有助于您自定义状态栏的外观。我更改您的CheckedChanged处理程序以查找StatusBar控件并向其添加文本。

检查以下代码：

    protected void Page_Load(object sender, EventArgs e)
    {
        for (int T = 0; T <= 26; T++)
        {
            Label x = new Label();
            x.ID = T.ToString();
            x.Text = "orem ipsum dolor sit amet, consectetur adipiscing elit. Nulla blandit id felis ac volutpat. Aenean tempor faucibus est, ac feugiat libero egestas sit amet. Aliquam";
            Label y = new Label();
            y.ID = "Title_" + T.ToString();
            y.Text = "Title " + T.ToString();

            RadioButton Radio1 = new RadioButton();
            Radio1.ID = "R_" + T.ToString();
            Radio1.Text = "Yes";
            Radio1.GroupName = "Radio_" + T.ToString();
            Radio1.CheckedChanged += new EventHandler(this.CheckedChanged);
            Radio1.AutoPostBack = true;
            RadioButton Radio2 = new RadioButton();
            Radio2.ID = "RX_" + T.ToString();
            Radio2.Text = "No";
            Radio2.GroupName = "Radio_" + T.ToString();
            Radio2.CheckedChanged += new EventHandler(this.CheckedChanged);
            Radio2.AutoPostBack = true;
            Panel StatusBar = new Panel();
            StatusBar.ID = "status_" + T.ToString();

            PlaceHolder pcl = new PlaceHolder();
            pcl.ID = "test_" + T.ToString();
            pcl.Controls.Add(y);
            pcl.Controls.Add(new LiteralControl("<br>"));
            pcl.Controls.Add(x);
            pcl.Controls.Add(new LiteralControl("<br>"));
            pcl.Controls.Add(Radio1);
            pcl.Controls.Add(Radio2);
            pcl.Controls.Add(new LiteralControl("<br><br>"));
            form1.Controls.Add(pcl);
            form1.Controls.Add(StatusBar);
        }
        //form1.Controls.Add(new PlaceHolder { ID = "MyStatusBar" });
    }
    protected void CheckedChanged(object sender, EventArgs e)
    {
        RadioButton tRadio = (RadioButton)sender;
        var T = tRadio.ID.Split('_')[1];
        var statusBarID = "status_" + T;
        var StatusBar = tRadio.Parent.FindControl(statusBarID) as Panel;
        if (tRadio.Text == "Yes")
        {
            StatusBar.Controls.Add(new LiteralControl("SampleText"));
        }

    }