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Answer 1

A:

Check this link on HierarchicalDataTemplate. There are given examples of using it with various types.

Eugene Cheverda 2010-07-16 08:56:32

That would be indeed the way I'd do it if I choose to restructure my whole ObservableCollection. I just feel that there should be a more convenient technique for this, like with LINQ queries or something...

Koen 2010-07-16 09:01:45

Answer 2

A:

Group your collection by setting GroupDescriptions on its CollectionViewSource. You can do it in code by doing something like this:

CollectionViewSource.GetDefaultView(yourCollection).GroupDescriptions.Add(
    new PropertyGroupDescription("PropertyName"));

Or you can do it in XAML by creating a CollectionViewSource explicitly.

    <CollectionViewSource
        Source="{StaticResource yourCollection}"
        xmlns:dat="clr-namespace:System.Windows.Data;assembly=PresentationFramework">
        <CollectionViewSource.GroupDescriptions>
            <dat:PropertyGroupDescription PropertyName="PropertyName"/>
        </CollectionViewSource.GroupDescriptions>
    </CollectionViewSource>

If you are using a plain ItemsControl like ListBox then you can just set the GroupStyle property. If you want to use a TreeView, then I think you want to bind to the Groups property on the ICollectionView. You should read Bea Stollnitz's blog entries on grouping:

Quartermeister 2010-07-16 12:39:47

Interesting but I'm not sure if I can use this. I need checkboxes in front of my items on both levels and checking a group should check all child items, etc. I did that now with code in my model.Also, if there's a way around that, I would still need to make PropertyName vary on the selection of radio buttons, which I believe cannot be done because it is not a DependencyProperty...

Koen 2010-07-16 12:59:51

@Koen: You could bind check boxes to the CollectionViewGroup with a custom converter that checks each child. For changing the grouping, you could do it in code, either in the code-behind or in your ViewModel, or you could just have two CollectionViewSources that are grouped in different ways and change which one you bind the TreeView to.

Quartermeister 2010-07-16 14:17:05

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Grouping data in WPF treeview

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