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Binding to Array and ArrayList

Binding RadTreeView to a data source that implements IEnumerable, such as Array or ArrayList, can create a flat data structure as well as a hierarchy if the proper ID -> ParentID relationship is provided.

Here is a general outline of IEnumerable data binding:

  1. Create the collection.

  2. Add values to the collection and set the DataSource property of RadTreeView to the instance of the collection.

  3. Call the DataBind() method.

The collection is automatically mapped to the Text property of the respective TreeView Node. The example below takes an array of strings as a data source.

RadTreeView Binding to Array

protected void Page_Load(object sender, EventArgs e)
{    
    if (!IsPostBack)    
    {
        string[] cars = new string[] {"Porsche Carrera","Ferrari F430","Aston Martin DB9"};
        RadTreeView1.DataSource = cars;        
        RadTreeView1.DataBind();    
    }
}
Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
    If Not IsPostBack Then
        Dim cars As String() = New String() {"Porsche Carrera", "Ferrari F430", "Aston Martin DB9"}
        RadTreeView1.DataSource = cars
        RadTreeView1.DataBind()
    End If
End Sub

If you have a collection (any collection implementing ICollection or IEnumerable) that contains objects (as opposed to simple values), you can take advantage of DataTextField, DataNavigateUrlField, and DataValueField properties to map object properties from the object directly to the Text, NavigateUrl or Value fields. If the DataFieldID and DataFieldParentID properties are set, RadTreeView will create a hierarchy of Nodes, determining the Root ones using the following algorithm:

tip

their DataFieldParentID property must be null if it is of nullable (e.g. int? ) or reference (e.g. string ) type.

example
ID ParentID
1 (null)
2 1

their DataFieldParentID property must return the default value if it is value type (e.g. 0 for int , Guid.Empty for Guid ).

example
ID ParentID
1 0
2 1

note

To see hierarchical data binding to IEnumerable in action, please visit the Hierarchical Data Binding live demo.

If you need to map additional properties from the object, subscribe to the NodeDataBound event. The event arguments passed to the event, e.NodeBound and e.NodeBound.DataItem, hold the instance of the TreeView Node being bound and the DataItem associated with the TreeView Node. You can then map a property from the DataItem (make sure to cast the DataItem object to your respective data type first) to a property of the RadTreeNode class.

The example below creates a list of car objects, each with properties for Name, Price and URL. DataTextField is bound to "Name", DataNavigateUrlField is bound to "URL" and DataValueField is bound to "Price". Note that the NodeDataBound event handler sets the Target property of each Node to _self so that the URL for each Node will display in a new window. When the Node is clicked, the Text and Value of the Node is displayed in the page title and the Node is selected. Navigation to the URL occurs automatically. Also notice that the NodeDataBound event handler sets the tooltip of the Node based on the Node DataItem. The DataItem is cast to the underlying Car object type.

RadTreeView Binding to Array

public partial class _Default : System.Web.UI.Page
{
   protected void Page_Load(object sender, EventArgs e)
   {
       if (!IsPostBack)
       {
           Car[] cars = new Car[] {
               new Car("Porsche Carrera", 79100, "http://www.google.com/search?q=Porsche"),
               new Car("Ferrari F430", 229955, "http://www.google.com/search?q=Ferrari"),
               new Car("Aston Martin DB9", 168000, "http://www.google.com/search?q=AstonMartin"),            
           };
           RadTreeView1.DataSource = cars;
           RadTreeView1.DataTextField = "Name";
           RadTreeView1.DataValueField = "Price";
           RadTreeView1.DataNavigateUrlField = "URL";
           RadTreeView1.DataBind();
       }
   }
   protected void RadTreeView1_NodeClick(object sender, Telerik.Web.UI.RadTreeNodeEventArgs e)
   {
       this.Title = e.Node.Text + " - Price:" + Convert.ToDouble(e.Node.Value).ToString("c");
       e.Node.Selected = true;
   }
   protected void RadTreeView1_NodeDataBound(object sender, Telerik.Web.UI.RadTreeNodeEventArgs e)
   {
       e.Node.Target = "_blank";       
       e.Node.ToolTip = "Top speed: " + (e.Node.DataItem as Car).TopSpeed.ToString() + "MPH";
   }
}

public class Car
{
   public Car(string name, double price, string url)
   {
       _name = name;
       _price = price;
       _url = url;
   }
   private string _name;
   public string Name
   {
       get { return _name; }
       set { _name = value; }
   }
   private double _price;
   public double Price
   {
       get { return _price; }
       set { _price = value; }
   }
   private string _url;
   public string URL
   {
       get { return _url; }
       set { _url = value; }
   }
} 
Partial Public Class _Default
    Inherits System.Web.UI.Page

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
        If Not IsPostBack Then
            Dim cars As Car() = New Car() {_
                      New Car("Porsche Carrera", 79100, "http://www.google.com/search?q=Porsche"), _
                      New Car("Ferrari F430", 229955, "http://www.google.com/search?q=Ferrari"), _
                      New Car("Aston Martin DB9", 168000, "http://www.google.com/search?q=AstonMartin")}

            RadTreeView1.DataSource = cars
            RadTreeView1.DataTextField = "Name"
            RadTreeView1.DataValueField = "Price"
            RadTreeView1.DataNavigateUrlField = "URL"
            RadTreeView1.DataBind()
        End If
    End Sub

    Protected Sub RadTreeView1_NodeClick(ByVal sender As Object, ByVal e As Telerik.Web.UI.RadTreeNodeEventArgs)
        Me.Title = e.Node.Text + " - Price:" + Convert.ToDouble(e.Node.Value).ToString("c")
        e.Node.Selected = True
    End Sub

    Protected Sub RadTreeView1_NodeDataBound(ByVal sender As Object, ByVal e As Telerik.Web.UI.RadTreeNodeEventArgs)
        e.Node.Target = "_blank"
        e.Node.ToolTip = "Top speed: " + (TryCast(e.Node.DataItem, Car)).TopSpeed.ToString() + "MPH"
    End Sub
End Class   

Public Class Car
    Public Sub New(ByVal name As String, ByVal price As Double, ByVal url As String)
        _name = name
        _price = price
        _url = url
    End Sub
    Private _name As String
    Public Property Name() As String
        Get
            Return _name
        End Get
        Set(ByVal value As String)
            _name = value
        End Set
    End Property
    Private _price As Double
    Public Property Price() As Double
        Get
            Return _price
        End Get
        Set(ByVal value As Double)
            _price = value
        End Set
    End Property
    Private _url As String
    Public Property URL() As String
        Get
            Return _url
        End Get
        Set(ByVal value As String)
            _url = value
        End Set
    End Property
End Class