How to: Create Nodes in Unbound Mode in Code

• Nov 13, 2018
• 2 minutes to read

The following code shows how to manually populate a TreeList control with nodes in unbound mode.

To add nodes in unbound mode, utilize the TreeList.AppendNode method. Data that is passed to this method must match the TreeList columns. So, the TreeList columns are created before the nodes are created.

Note that calls to the methods used to create nodes are wrapped with the TreeList.BeginUnboundLoad and TreeList.EndUnboundLoad methods. This reduces the control’s updates to a minimum, and thus improves performance.

The following image displays the result.

C#

using DevExpress.XtraTreeList;
using DevExpress.XtraTreeList.Columns;
using DevExpress.XtraTreeList.Nodes;

private void Form1_Load(object sender, EventArgs e) {
    CreateColumns(treeList1);
    CreateNodes(treeList1);
}

private void CreateColumns(TreeList tl) {
    // Create three columns
    tl.BeginUpdate();
    TreeListColumn col1 = tl.Columns.Add();
    col1.FieldName = "Customer";
    col1.Caption = "Customer";
    col1.VisibleIndex = 0;
    TreeListColumn col2 = tl.Columns.Add();
    col2.FieldName = "Location";
    col2.Caption = "Location";
    col2.VisibleIndex = 1;
    TreeListColumn col3 = tl.Columns.Add();
    col3.FieldName = "Phone";
    col3.Caption = "Phone";
    col3.VisibleIndex = 2;
    tl.EndUpdate();
}

private void CreateNodes(TreeList tl) {
    tl.BeginUnboundLoad();
    // Create a root node
    TreeListNode parentForRootNodes = null;
    TreeListNode rootNode = tl.AppendNode(
        new object[] { "Alfreds Futterkiste", "Germany, Obere Str. 57", "030-0074321" },
        parentForRootNodes);
    // Create a child of the rootNode
    tl.AppendNode(new object[] { "Suyama, Michael", "Obere Str. 55", "030-0074263" }, rootNode);
    // Create more nodes
    // ...
    tl.EndUnboundLoad();
}

VB.NET

Imports DevExpress.XtraTreeList
Imports DevExpress.XtraTreeList.Columns
Imports DevExpress.XtraTreeList.Nodes

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    CreateColumns(treeList1)
    CreateNodes(treeList1)
End Sub

Private Sub CreateColumns(ByVal tl As TreeList)
    ' Create three columns
    tl.BeginUpdate()
    Dim col1 As TreeListColumn = tl.Columns.Add()
    col1.FieldName = "Customer"
    col1.Caption = "Customer"
    col1.VisibleIndex = 0
    Dim col2 As TreeListColumn = tl.Columns.Add()
    col2.FieldName = "Location"
    col2.Caption = "Location"
    col2.VisibleIndex = 1
    Dim col3 As TreeListColumn = tl.Columns.Add()
    col3.FieldName = "Phone"
    col3.Caption = "Phone"
    col3.VisibleIndex = 2
    tl.EndUpdate()
End Sub

Private Sub CreateNodes(ByVal tl As TreeList)
    tl.BeginUnboundLoad()
    ' Create a root node
    Dim parentForRootNodes As TreeListNode = Nothing
    Dim rootNode As TreeListNode = tl.AppendNode(New Object() { "Alfreds Futterkiste", "Germany, Obere Str. 57", "030-0074321" }, parentForRootNodes)
    ' Create a child of the rootNode
    tl.AppendNode(New Object() { "Suyama, Michael", "Obere Str. 55", "030-0074263" }, rootNode)
    ' Create more nodes
    ' ...
    tl.EndUnboundLoad()
End Sub