IsExpandedBinding and IsExpandableBinding

Since Q1 2013 release, RadTreeListView has two new properties - IsExpandedBinding and IsExpandableBinding which can be used to synchronize its expanded and expandable states with your view-model.

Binding to the IsExpanded property of TreeListViewRow is not fully supported. You can consider using IsExpandedBinding property instead.

Use of IsExpandedBinding

IsExpandedBinding property can be used to show you whether a TreeListView's row is expanded or not.

Follow these steps to accomplish the task:

1. For the purpose of this tutorial we will add a boolean property - IsExpanded to our WarehouseItem collection:

   Please, note that our WarehouseItem class implements the INotifyPropertyChanged interface.

       public class WarehouseItem : INotifyPropertyChanged
       {
           public event PropertyChangedEventHandler PropertyChanged;
   
           private bool isExpanded;
           private string name;
           private int count;
   
           public WarehouseItem(string name, int count, bool isExpanded = true)
           {
               this.Name = name;
               this.IsExpanded = isExpanded;           
           }
   
           public string Name
           {
               get
               {
                   return this.name;
               }
               set
               {
                   if (value != this.name)
                   {
                       this.name = value;
                       this.OnPropertyChanged("Name");
                   }
               }
           }
   
           public bool IsExpanded
           {
               get
               {
                   return this.isExpanded;
               }
               set
               {
                   if (value != this.isExpanded)
                   {
                       this.isExpanded = value;
                       this.OnPropertyChanged("IsExpanded");
                   }
               }
           }
       protected virtual void OnPropertyChanged(PropertyChangedEventArgs args)
           {
               PropertyChangedEventHandler handler = this.PropertyChanged;
               if (handler != null)
               {
                   handler(this, args);
               }
           }
   
           private void OnPropertyChanged(string propertyName)
           {
               this.OnPropertyChanged(new PropertyChangedEventArgs(propertyName));
           }
   

       Public Class WarehouseItem
           Implements INotifyPropertyChanged
           Public Event PropertyChanged As PropertyChangedEventHandler
   
           Private m_isExpanded As Boolean
           Private m_name As String
           Private count As Integer
   
           Public Sub New(name As String, count As Integer, Optional isExpanded As Boolean = True)
               Me.Name = name
               Me.IsExpanded = isExpanded
           End Sub
   
           Public Property Name() As String
               Get
                   Return Me.m_name
               End Get
               Set(value As String)
                   If value <> Me.m_name Then
                       Me.m_name = value
                       Me.OnPropertyChanged("Name")
                   End If
               End Set
           End Property
   
           Public Property IsExpanded() As Boolean
               Get
                   Return Me.m_isExpanded
               End Get
               Set(value As Boolean)
                   If value <> Me.m_isExpanded Then
                       Me.m_isExpanded = value
                       Me.OnPropertyChanged("IsExpanded")
                   End If
               End Set
           End Property
           Protected Overridable Sub OnPropertyChanged(args As PropertyChangedEventArgs)
               Dim handler As PropertyChangedEventHandler = Me.PropertyChanged
               RaiseEvent handler(Me, args)
           End Sub
   
           Private Sub OnPropertyChanged(propertyName As String)
               Me.OnPropertyChanged(New PropertyChangedEventArgs(propertyName))
           End Sub
       End Class
   

2. Add RadTreeListView as demonstrated below:

       <telerik:RadTreeListView x:Name="radTreeListView"
                                    IsExpandedBinding="{Binding IsExpanded, Mode=TwoWay}"
                                    AutoGenerateColumns="False">
               <telerik:RadTreeListView.ChildTableDefinitions>
                   <telerik:TreeListViewTableDefinition ItemsSource="{Binding Items}" />
               </telerik:RadTreeListView.ChildTableDefinitions>
               <telerik:RadTreeListView.Columns>
                   <telerik:GridViewDataColumn DataMemberBinding="{Binding Name}"
                                       Header="Name" />
                   <telerik:GridViewDataColumn DataMemberBinding="{Binding IsExpanded}" 
                                       Header="Is Expanded" />
               </telerik:RadTreeListView.Columns>
           </telerik:RadTreeListView>
   

3. Here is a snapshot of the result:

A complete example of using RadTreeListView's IsExpandedBinding property is available in the TreeListView's IsExpanded demo.

Use of IsExpandableBinding

The use of IsExpandableBinding would be similar as shown for the IsExpandedBinding.

A complete example of using RadTreeListView's IsExpandedBinding property is available in the TreeListView's OnDemandDataLoading demo.