Similar to this post, I’ve made a similar example on how to load on demand RadTreeView for Silverlight three level hierarchy using MVVM and OData service:
XAML
<UserControl.Resources>
<DataTemplate x:Key="OrderDetailsTemplate">
<Grid>
...
</Grid>
</DataTemplate>
<telerik:HierarchicalDataTemplate x:Key="OrderTemplate"
ItemsSource="{Binding OrderDetailsCollection}"
ItemTemplate="{StaticResource OrderDetailsTemplate}">
<StackPanel Orientation="Horizontal">
...
</StackPanel>
</telerik:HierarchicalDataTemplate>
<telerik:HierarchicalDataTemplate x:Key="CompanyTemplate"
ItemsSource="{Binding OrdersCollection}"
ItemTemplate="{StaticResource OrderTemplate}">
<StackPanel Orientation="Horizontal">
...
</StackPanel>
</telerik:HierarchicalDataTemplate>
</UserControl.Resources>
<Grid x:Name="LayoutRoot" Background="White">
<telerik:RadTreeView x:Name="treeView1" ItemsSource="{Binding CustomersCollection}"
ItemTemplate="{StaticResource CompanyTemplate}" />
</Grid>
C#
public partial class MainPage : UserControl
{
public MainPage()
{
InitializeComponent();
DataContext = new NorthwindEntities();
}
}
The approach is the same as in the RadGridView post. Again, I’ve used partial classes to extend generated code for the service
reference:
C#
public partial class NorthwindEntities
{
public NorthwindEntities()
{
//
}
DataServiceCollection<Customer> _CustomersCollection;
public DataServiceCollection<Customer> CustomersCollection
{
get
{
if (_CustomersCollection == null)
{
_CustomersCollection = new DataServiceCollection<Customer>(this);
_CustomersCollection.CollectionChanged += (s, e) =>
{
if (e.Action == System.Collections.Specialized.NotifyCollectionChangedAction.Add)
{
foreach (var c in e.NewItems.OfType<Customer>())
{
c.Context = this;
}
}
else if (e.Action == System.Collections.Specialized.NotifyCollectionChangedAction.Remove)
{
foreach (var c in e.OldItems.OfType<Customer>())
{
c.Context = null;
}
}
};
_CustomersCollection.LoadAsync(this.Customers);
}
return _CustomersCollection;
}
}
}
and as you can see I’ve passed the context itself to the entities in
order to create queries for child data:
C#
public partial class Customer
{
public Customer()
{
_Orders = null;
}
internal NorthwindEntities Context { get; set; }
public DataServiceCollection<Order> OrdersCollection
{
get
{
if (_Orders == null && Context != null)
{
_Orders = new DataServiceCollection<Order>(Context);
_Orders.CollectionChanged += (s, e) =>
{
if (e.Action == System.Collections.Specialized.NotifyCollectionChangedAction.Add)
{
foreach (var c in e.NewItems.OfType<Order>())
{
c.Context = this.Context;
}
}
else if (e.Action == System.Collections.Specialized.NotifyCollectionChangedAction.Remove)
{
foreach (var c in e.OldItems.OfType<Order>())
{
c.Context = null;
}
}
};
_Orders.LoadAsync(from o in Context.Orders
where o.CustomerID == CustomerID
select o);
}
return _Orders;
}
}
}
Demo: TreeView, MVVM and OData
In addition, you can check our online TreeView OData example.