在占位符中查找控件

我正在使用AJAX来创建一个用户控件，其中包含一个包含label和RadioButtonList或CheckBoxList的面板。 在.aspx页面中有一个占位符，该控件应该在其中。我需要从占位符中找到List我试过这个：

public static int id = 1; QuestionPanelControl q1 ; protected void Page_Load(object sender, EventArgs e) { if (!Page.IsPostBack) { LoadQuestionPanelControl(); } } //Next Button protected void Button1_Click(object sender, EventArgs e) { id++; if (id <= 10) { //LoadQuestionPanelControl(); PlaceHolder p = (PlaceHolder)Page.FindControl("PlaceHolder1"); QuestionPanelControl c1 = (QuestionPanelControl)p.FindControl("QuestionPanelControl1"); // QuestionPanelControl c1 = (QuestionPanelControl)p.FindControl("Panel_Question"); RadioButtonList rb = c1.ChildRadioButtonList; if (rb.SelectedIndex == 0) { //DB } else if (rb.SelectedIndex == 1) { //DB } else { Lsb_Unanswered.Items.Add("Question #" + id); } LoadQuestionPanelControl(); } } public void LoadQuestionPanelControl() { Session.Add("ID",id); q1= new QuestionPanelControl(); q1.ID = "QuestionPanelControl1"; Control c = Page.LoadControl("QuestionPanelControl.ascx"); PlaceHolder1.Controls.Clear(); PlaceHolder1.Controls.Add(c); } 

当我使用断点时，我发现p的Controls属性为0。

注意：ChildRadioButtonList是QuestionPanelControl中的属性。 有什么建议…

Answer 1

试试这段代码：

 PlaceHolder p = (PlaceHolder)FindControlRecursive(Page, "PlaceHolder1"); public static Control FindControlRecursive(Control ctrl, string controlID) { if (string.Compare(ctrl.ID, controlID, true) == 0) { // We found the control! return ctrl; } else { // Recurse through ctrl's Controls collections foreach (Control child in ctrl.Controls) { Control lookFor = FindControlRecursive(child, controlID); if (lookFor != null) return lookFor; // We found the control } // If we reach here, control was not found return null; } } 

Answer 2

编辑：

  public void LoadQuestionPanelControl() { Session.Add("ID",id); Control c = Page.LoadControl("QuestionPanelControl.ascx"); var q1= c as QuestionPanelControl; if(q1 != null) { q1.ID = "QuestionPanelControl1"; PlaceHolder1.Controls.Clear(); PlaceHolder1.Controls.Add(q1); } } 

并查看占位符的Controls.Count是否为0以外的值。