Hi Roman,
Supposing that you want to do custom filtering and you don't want to change the ViewModels, I suggest you to do re-binding when you filter. For instance, you can dynamically change the ItemsSource of the RadTreeView by first making a copy of the initial data and then filtering it or using a
Linq methods that return IEnumerable when applied to ObservableCollection (probably the type of your ItemsSource collection). Please let us know if this is suitable for you.
Best wishes,
Petar Mladenov
the Telerik team
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