Setting "IsExpanded" on Templated Node

[Phil Cockfield]

I'm using the 'ItemTemplate' for the RadTreeView control like this:

    <UserControl.Resources>
        <!--Tree Node-->
        <tcore:HierarchicalDataTemplate x:Key="node">
            <StackPanel Orientation="Horizontal">
                <Image Source="{Binding Icon}" Margin=" 0,0,6,0" />
                <TextBlock Text="{Binding Text}"  />
            </StackPanel>
        </tcore:HierarchicalDataTemplate>
    </UserControl.Resources>

    <!--TreeView-->
    <t:RadTreeView
                ItemsSource="{Binding Nodes}"
                ItemTemplate="{StaticResource node}"
                IsLineEnabled="True" />

I'm wondering, within my "node" template, how can I get set whether the node IsExpanded of not.  Like the way you could do it if you were using:

            <t:RadTreeViewItem
                        DefaultImageSrc="{Binding Icon}"
                        Header="{Binding Text}"
                        IsExpanded="True" ItemsSource="{Binding Children}" />

Do I have to wrap my templated XAML in something.  Putting a RadTreeViewItem within the template caused the control to crash, so I'm not sure what the right way is to approach this.

Thanks for your help!

[Valentin.Stoychev]

Hi Phil Cockfield,

The ItemTemplate property is used for templating how the Header of the item will look like.

The IsExpanded property should be set via style. So you will need to define the ItemContainerStyle property of the RadTreeView and set the IsExpanded to True there. Here is a sample:

// declare the style

 

 

<UserControl.Resources>

 

 

 

<Style TargetType="telerikNavigation:RadTreeViewItem" x:Key="TreeItemTemplate">

 

 

 

<Setter Property="IsExpanded" Value="True"/>

 

 

 

</Style>

 

 

 

</UserControl.Resources>

 

// set the style to the TreeView

<

 

telerikNavigation:RadTreeView ItemContainerStyle="{StaticResource TreeItemTemplate}"

 

Kind regards,
Valentin.Stoychev
the Telerik team

Instantly find answers to your questions on the new Telerik Support Portal.
Watch a video on how to optimize your support resource searches and check out more tips on the blogs.

[Phil Cockfield]

Thanks Valentin.  I just tried that and it didn't work.  See code:

<ResourceDictionary
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:Quest.Core.UI.Controls"
    xmlns:t="clr-namespace:Telerik.Windows.Controls;assembly=Telerik.Windows.Controls.Navigation"
    xmlns:tcore="clr-namespace:Telerik.Windows.Controls;assembly=Telerik.Windows.Controls">

    <ControlTemplate x:Key="TreeView" TargetType="local:TreeView">
        <Border>
            <Border.Resources>
                <!--Tree Node-->
                <tcore:HierarchicalDataTemplate x:Key="node" ItemsSource="{Binding Children}">
                    <StackPanel Orientation="Horizontal">
                        <Image Source="{Binding Icon}" Margin=" 0,0,6,0" />
                        <TextBlock Text="{Binding Text}"  />
                    </StackPanel>
                </tcore:HierarchicalDataTemplate>

                <Style x:Key="TreeItemTemplate" TargetType="t:RadTreeViewItem">
                    <Setter Property="IsExpanded" Value="True"/>
                </Style>

            </Border.Resources>

            <!--TreeView-->
            <t:RadTreeView
                ItemsSource="{Binding Nodes}"
                IsLineEnabled="True"

                ItemTemplate="{StaticResource node}"
                ItemContainerStyle="{StaticResource TreeItemTemplate}"

                Padding="{TemplateBinding Padding}"
                Background="{TemplateBinding Background}"
                BorderBrush="{TemplateBinding BorderBrush}"
                BorderThickness="{TemplateBinding BorderThickness}" />
        </Border>
    </ControlTemplate>
</ResourceDictionary>

What am I doing wrong here?

If it did work, I can't see how it gets to the solution I need which is to be able to control the 'IsExpanded' state (open/close) via data-binding from the model. I would envision the above code forcing all nodes to be open (IsExpanded=true) because the value is set at the root TreeView level.

Thanks for any more answers you might have!

[Phil Cockfield]

Opps - sorry, yes that is causing them all to be expanded.

However my secondary question below still stands.  How can I structure this so that I can set the 'IsExpanded' value for each node via data-binding to the model bound to the Node's data-context?

Thanks!

[Valentin.Stoychev]

Hi Phil Cockfield,

To achieve this you need to use our inhouse developed container bindings:
1. Here is how to define the bindings to your bussines object:

 

 

<telerik:ContainerBindingCollection x:Key="containerBindings">

 

 

 

<telerik:ContainerBinding PropertyName="Header" Binding="{Binding Caption}" />

 

 

 

<telerik:ContainerBinding PropertyName="IsExpanded" Binding="{Binding Expanded}" />

 

 

 

</telerik:ContainerBindingCollection>

 

2. Declare the bindings for the data template:

<

 

DataTemplate x:Key="MyTemplate" telerik:ContainerBinding.ContainerBindings="{StaticResource containerBindings}" >

 

 

 

<TextBlock Text="{Binding}"/>

 

 

 

</DataTemplate>

 

Then ofcouse set the DataTemplate as an ItemTemplate. What the container bindings will do is they will bind a property from the RadTreeViewItem ( the container) to a property of your bussinse object. In our case it will bind the Header property of the RadTreeViewITem to the Caption property of the bussines object.

Please let us know how it goes and if you have any other questions.


Sincerely yours,
Valentin.Stoychev
the Telerik team

Instantly find answers to your questions on the new Telerik Support Portal.
Watch a video on how to optimize your support resource searches and check out more tips on the blogs.