在占位符中查找控件

本文关键字：控件 查找 占位符 | 更新日期: 2023-09-27 17:48:59

我使用AJAX使一个用户控件，其中包含一个面板，根据条件包含标签和RadioButtonList或CheckBoxList。在.aspx页面中有一个占位符，该控件应该在其中。我需要从占位符找到列表我试过了:

 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:childadiobuttonlist是QuestionPanelControl中的一个属性。什么建议…

在占位符中查找控件

试试下面的代码:

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;
 }
}

EDIT: 

   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);
        }
    }

，看看控件是否。占位符的计数不是0。

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