c# - 找不到动态添加的 UserControl .Net 的实例

Question

我有一个 UserControl，我正在将其加载到 UpdatePanel 内的一个 div 中。这是我加载它的代码:

controls.IDLControl IdlControl = LoadControl(@"~/controls/IDLControl.ascx") as controls.IDLControl;
IdlControl.ClientIDMode = ClientIDMode.Static;
IdlControl.ID = "IDLControl";
spGroup.Controls.Clear();
spGroup.Controls.Add(IdlControl);

这是我尝试检索它的实例的代码:

controls.IDLControl IdlControl = RecursiveFindControl(this, "IDLControl") as controls.IDLControl;

private Control RecursiveFindControl(Control targetControl, string findControlId) {
    if (targetControl.HasControls()) {
        foreach (Control childControl in targetControl.Controls) {
            if (childControl.ID == findControlId) {
                return childControl;
            }

            RecursiveFindControl(childControl, findControlId);
        }
    }

    return null;
}

但是，我得到的只是空值。我需要帮助来解决这个问题。

AFAIK，我需要在预初始化时将控件重新添加到页面，但它是可以添加的控件之一，具体取决于从下拉列表(也是动态填充)中选择的选项。我被困在想弄清楚如何使这项工作。

Answer 1

您可以尝试这样的操作，根据您在 DropDownList 中选择的选项将您的控件添加回 Page_Init。

protected void Page_Init(Object sender, EventArgs e)
{
    if (IsPostBack)
    {
        if (drpYourDropDown.Items.Count > 0 && drpYourDropDown.SelectedItem.Text == "yourOption")
        { 
            AddIDLControl();
        }
    }
}

private void AddIDLControl()
{
    controls.IDLControl IdlControl = LoadControl(@"~/controls/IDLControl.ascx") as controls.IDLControl;
    IdlControl.ClientIDMode = ClientIDMode.Static;
    IdlControl.ID = "IDLControl";
    spGroup.Controls.Clear();
    spGroup.Controls.Add(IdlControl);
}