DropDownTree HeaderTemplate dynamic

[Jerome MAILLEY]

Hi,

First of all, I'm using the latest version of your Telerik.Web.UI.dll (2016.3.914.40). I'm trying to set RadDropDownTree HeaderTemplate dynamically as I did for RadComboBox. Here is my code :

 

<telerik:RadDropDownTree ID="RadDropDownTree" runat="server" EnableViewState="false" CheckBoxes="None"      OnNodeDataBound="RadDropDownTree_NodeDataBound" <br>    DataFieldID="ID" DataFieldParentID="ParentID" DataTextField="Text" DataValueField="Value"<br>    Width="100%" RenderMode="Lightweight" Visible="false" Skin="Metro"><br></telerik:RadDropDownTree>

[Jerome MAILLEY]

protected void Page_Load(object sender, EventArgs e){
//....
RadDropDownTree.HeaderTemplate = new HeaderTemplate(headerItem);
//....
}

public class HeaderTemplate : ITemplate {
ComboBoxItem _headerItem;
public HeaderTemplate(ComboBoxItem headerItem) {
this._headerItem = headerItem;
}
public void InstantiateIn(Control container) {
if (!string.IsNullOrEmpty(_headerItem.Code))
{
Label labelCode = new Label();
labelCode.Font.Bold = true;
labelCode.Text = _headerItem.Code;
container.Controls.Add(labelCode);
Label labelDash = new Label();
labelDash.Text = " - ";
container.Controls.Add(labelDash);
}
Label labelLabel = new Label();
labelLabel.Font.Italic = true;
labelLabel.Text = _headerItem.Label;
container.Controls.Add(labelLabel);
}
}
public class ComboBoxItem{
public string Code { get; set; }
public string Label { get; set; }
}

[Jerome MAILLEY]

However, it's does not work. Its seems that ITemplate is not made for RadDropDownTree HeaderTemplate : the InstantiateIn function is never called. Is there a way to make it work ?

 

Thanks

[Ivan Danchev]

Hello Jerome,

The DropDownTree is initialized earlier, thus its HeaderTemplate has to be set earlier than the page's Load event - in the PreInit event:

protected void Page_PreInit(object sender, EventArgs e)
{
    RadDropDownTree1.HeaderTemplate = new HeaderTemplate(headerItem);
}

Regards,
Ivan Danchev
Telerik by Progress

[Jerome MAILLEY]

Hello Ivan,

I cannot use the Page_PreInit function because the RadDropDownTree is in a UserControl so it's not fired.

According to this, I tried the following code but it does not work either:

protected void Page_Init(object sender, EventArgs e)
{
    RadDropDownTree1.HeaderTemplate = new HeaderTemplate(headerItem);
}

 

I hope you will help me to figure it out.

Thanks,

 

[Ivan Danchev]

Hello Jerome,

As I explained in my previous reply, due to the early initialization of the DropDownTree the template must be set in the PreInit event. Both the Init and Load events are fired too late, thus neither the main page's nor the  UserControl's Init and Load events are not suitable for setting the template.

Regards,
Ivan Danchev
Telerik by Progress