WPF TreeView template with different classes

Question

How to write XAML for WPF TreeView so when I bind ViewModel with following structure?

public class A
{
    int Id { get; set; }
    string Name { get; set; }
             


        

Answer 1

You could combine the ItemsB and ItemsC collections of class A into a CompositeCollection.

Since HierarchicalDataTemplate.ItemsSource is not a collection, but a BindingBase it seems not possible to do this directly in XAML. You may however write a Binding Converter:

public class ClassAItemsConverter : IValueConverter
{
    public object Convert(
        object value, Type targetType, object parameter, CultureInfo culture)
    {
        var a = (A)value;

        return new CompositeCollection
        {
            new CollectionContainer() { Collection = a.ItemsB },
            new CollectionContainer() { Collection = a.ItemsC }
        };
    }

    public object ConvertBack(
        object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotSupportedException();
    }
}

The templates would look like this: