Deselecting Selected Items

[Glenn]

I have a RadTreeView where the SelectionMode = "Multiple".  However, I only want nodes to remain selected if they are on the same level.  For instance, if two nodes are selected on level 1 and a node on level 2 is selected, I want the two nodes on level 1 to be deselected and the only node to be selected is the node on level 2.

I read this Knowledge Base Article and implemented the ContainerBindingCollection.  However, when I set the Selected property of the object in the SelectedItems collection of the Tree, the selected nodes still remain selected.

Below is the markup for the xaml:

        <telerik:ContainerBindingCollection x:Name="BindingsCollection">
            <telerik:ContainerBinding PropertyName="IsSelected" Binding="{Binding Selected, Mode=TwoWay}" />
            <telerik:ContainerBinding PropertyName="IsExpanded" Binding="{Binding Expanded, Mode=TwoWay}" />
        </telerik:ContainerBindingCollection>

        <telerik:HierarchicalDataTemplate
            x:Key="UserTemplate"
            telerik:ContainerBinding.ContainerBindings="{StaticResource BindingsCollection}">
            <StackPanel Orientation="Horizontal">
                <Image Source="Assets/Images/user.png"/>
                <TextBlock Margin="5,0,0,0"  Text="{Binding UserName}" />
            </StackPanel>
        </telerik:HierarchicalDataTemplate>

        <telerik:HierarchicalDataTemplate
            x:Key="MembershipTemplate"
            ItemTemplate="{StaticResource UserTemplate}"
            ItemsSource="{Binding User}"
            telerik:ContainerBinding.ContainerBindings="{StaticResource BindingsCollection}" >
            <StackPanel Orientation="Horizontal">
                <Image Source="Assets/Images/pkg.png"/>
                <TextBlock Margin="5,0,0,0"  Text="{Binding Name}" />
            </StackPanel>
        </telerik:HierarchicalDataTemplate>

        <telerik:HierarchicalDataTemplate
            x:Key="FacilityTemplate"
            ItemTemplate="{StaticResource MembershipTemplate}"
            ItemsSource="{Binding Membersip}"
            telerik:ContainerBinding.ContainerBindings="{StaticResource BindingsCollection}">
            <StackPanel Orientation="Horizontal">
                <Image Source="Assets/Images/house.png"/>
                <TextBlock Margin="5,0,0,0"  Text="{Binding Name}" />
            </StackPanel>
        </telerik:HierarchicalDataTemplate>
        <telerik:HierarchicalDataTemplate
            x:Key="OrderTemplate"
            ItemTemplate="{StaticResource FacilityTemplate}"
            ItemsSource="{Binding Facility}"
            telerik:ContainerBinding.ContainerBindings="{StaticResource BindingsCollection}">
            <StackPanel Orientation="Horizontal">
                <Image Source="Assets/Images/book.png"/>
                <TextBlock Margin="5,0,0,0"  Text="Order: " /><TextBlock Text="{Binding OrderNumber}" />
            </StackPanel>
        </telerik:HierarchicalDataTemplate>

Below is how I spin throw the SelectedItems collection and set the Selected property to false:

            foreach (var obj in this.RadTreeView1.SelectedItems) {
                if (!obj.GetType().Equals(item.Header.GetType())) {
                    ((MyModelBase)obj).Selected = false;
                }
            }

How can I deselect selected nodes?

Thanks,
Glenn

[Tina Stancheva]

Hi Glenn,

Please accept my apology for the delayed response.

The best way to accomplish your scenario in Silverlight is in the ViewModel classes or the business classes. I prepared a sample project illustrating this approach.

However, if you prefer to spin through the SelectedItems collection you can use the PreviewSelected event handler of the RadTreeView:

private void treeView_PreviewSelected(object sender, Telerik.Windows.RadRoutedEventArgs e)
{
    RadTreeViewItem item = e.Source as RadTreeViewItem;
    foreach (var obj in this.treeView.SelectedItems)
    {
        if (!obj.GetType().Equals(item.Header.GetType()))
        {
            if (obj is Company)
                ((Company)obj).IsSelected = false;
            else if (obj is Department)
                ((Department)obj).IsSelected = false;
            else
                ((Employee)obj).IsSelected = false;
        }
    }
}

Please keep in mind that the business classes need to implement INotifyPropertyChanged.

Take a look at the project and let me know if it works for you or if you need more info.

Sincerely yours,
Tina Stancheva
the Telerik team

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[Glenn]

Thank you very much Tina for your reply and sample code.

I implement INotifyPropertyChanged interface in my business objects and raise the PropertyChange event as you suggested.  I loop through the SelectedItems collection in the PreviewSelected event and it works perfectly.

Thanks,
Glenn

[Tina Stancheva]

Hi Glenn,

I am glad that I was able to help.

Please let us know if we can further assit you.

Greetings,
Tina Stancheva
the Telerik team

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[Madhu]

Hi Tina,

Can the same thing be achieved only using XAML? I mean by simple databinding instead of writing code for the treeview event?

Writing a data trigger to retrieve a boolean value from the view model and using that to assign the 'IsSelected' property of the RadTreeViewItem to false.

If the above is possible, kindly provide a sample.

A scenario that would call for this is where there would be a need to restrict selecting a parent item along with a child item. In other words, allowing either only multiple parent items or multiple child items to get selected.

Warm Regards
Madhu

[Hristo]

Hi Madhu,

The best way to implement your custom logic is to put it into the view model. I suppose you do not want to "pollute" the code behind with unnecessary event handlers? So, using PreviewSelected event handler can be avoided by placing the logic inside view model object. The project sent by my colleague Tina shows how to do it.

If you want to use only xaml to accomplish the scenario, I'm afraid it is not possible. Or at least it is not easy and straightforward.

Hope this helps. Please let us know if you need more info.

Kind regards,
Hristo Milyakov
the Telerik team