How to: Iterate Through Nodes via the Node Iterator

• Jun 07, 2019
• 6 minutes to read

This example shows how to traverse through all visible nodes and expand only those nodes that have more than four child nodes. Nodes that have less than four child nodes are collapsed.

View Example

MainWindow.xaml.vb

Imports Microsoft.VisualBasic
Imports System.Windows
Imports DevExpress.Xpf.Grid

Namespace DXTreeList_NodeTraversing
    ''' <summary>
    ''' Interaction logic for MainWindow.xaml
    ''' </summary>
    Partial Public Class MainWindow
        Inherits Window
        Public Sub New()
            InitializeComponent()
            treeListControl1.ItemsSource = Stuff.GetStuff()
        End Sub

        Private Sub treeListControl1_Loaded(ByVal sender As Object, ByVal e As RoutedEventArgs)
            SmartExpandNodes(4)
        End Sub

        Private Sub SmartExpandNodes(ByVal minChildCount As Integer)
            Dim nodeIterator As New TreeListNodeIterator(treeListView1.Nodes, True)
            Do While nodeIterator.MoveNext()
                nodeIterator.Current.IsExpanded = nodeIterator.Current.Nodes.Count >= minChildCount
            Loop
        End Sub
    End Class
End Namespace

MainWindow.xaml

<Window x:Class="DXTreeList_NodeTraversing.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525"
        xmlns:sys="clr-namespace:System;assembly=mscorlib"
        xmlns:dxg="http://schemas.devexpress.com/winfx/2008/xaml/grid"
        xmlns:dx="http://schemas.devexpress.com/winfx/2008/xaml/core">
    <Grid>
        <dxg:TreeListControl Name="treeListControl1" Loaded="treeListControl1_Loaded" >
            <dxg:TreeListControl.Columns>
                <dxg:TreeListColumn FieldName="Name" />
                <dxg:TreeListColumn FieldName="Department" />
                <dxg:TreeListColumn FieldName="Position" />
            </dxg:TreeListControl.Columns>
            <dxg:TreeListControl.View>
                <dxg:TreeListView Name="treeListView1" AutoWidth="True" ShowIndicator="False"
                                  KeyFieldName="ID" ParentFieldName="ParentID">
                    <!--<dxg:TreeListView.RootValue>
                        <sys:Int32>1</sys:Int32>
                    </dxg:TreeListView.RootValue>-->
                </dxg:TreeListView>
            </dxg:TreeListControl.View>
        </dxg:TreeListControl>
    </Grid>
</Window>

Employees.vb

Imports Microsoft.VisualBasic
Imports System
Imports System.Collections.Generic

Namespace DXTreeList_NodeTraversing

    Public Class Employee
        Private privateID As Integer
        Public Property ID() As Integer
            Get
                Return privateID
            End Get
            Set(ByVal value As Integer)
                privateID = value
            End Set
        End Property
        Private privateParentID As Integer
        Public Property ParentID() As Integer
            Get
                Return privateParentID
            End Get
            Set(ByVal value As Integer)
                privateParentID = value
            End Set
        End Property
        Private privateName As String
        Public Property Name() As String
            Get
                Return privateName
            End Get
            Set(ByVal value As String)
                privateName = value
            End Set
        End Property
        Private privatePosition As String
        Public Property Position() As String
            Get
                Return privatePosition
            End Get
            Set(ByVal value As String)
                privatePosition = value
            End Set
        End Property
        Private privateDepartment As String
        Public Property Department() As String
            Get
                Return privateDepartment
            End Get
            Set(ByVal value As String)
                privateDepartment = value
            End Set
        End Property
    End Class

    Public NotInheritable Class Stuff
        Private Sub New()
        End Sub
        Public Shared Function GetStuff() As List(Of Employee)
            Dim stuff As New List(Of Employee)()
            stuff.Add(New Employee() With {.ID = 1, .ParentID = 0, .Name = "Gregory S. Price", .Department = "", .Position = "President"})
            stuff.Add(New Employee() With {.ID = 2, .ParentID = 1, .Name = "Irma R. Marshall", .Department = "Marketing", .Position = "Vice President"})
            stuff.Add(New Employee() With {.ID = 3, .ParentID = 1, .Name = "John C. Powell", .Department = "Operations", .Position = "Vice President"})
            stuff.Add(New Employee() With {.ID = 4, .ParentID = 1, .Name = "Christian P. Laclair", .Department = "Production", .Position = "Vice President"})
            stuff.Add(New Employee() With {.ID = 5, .ParentID = 1, .Name = "Karen J. Kelly", .Department = "Finance", .Position = "Vice President"})

            stuff.Add(New Employee() With {.ID = 6, .ParentID = 2, .Name = "Brian C. Cowling", .Department = "Marketing", .Position = "Manager"})
            stuff.Add(New Employee() With {.ID = 7, .ParentID = 2, .Name = "Thomas C. Dawson", .Department = "Marketing", .Position = "Manager"})
            stuff.Add(New Employee() With {.ID = 8, .ParentID = 2, .Name = "Angel M. Wilson", .Department = "Marketing", .Position = "Manager"})
            stuff.Add(New Employee() With {.ID = 9, .ParentID = 2, .Name = "Bryan R. Henderson", .Department = "Marketing", .Position = "Manager"})

            stuff.Add(New Employee() With {.ID = 10, .ParentID = 3, .Name = "Harold S. Brandes", .Department = "Operations", .Position = "Manager"})
            stuff.Add(New Employee() With {.ID = 11, .ParentID = 3, .Name = "Michael S. Blevins", .Department = "Operations", .Position = "Manager"})
            stuff.Add(New Employee() With {.ID = 12, .ParentID = 3, .Name = "Jan K. Sisk", .Department = "Operations", .Position = "Manager"})
            stuff.Add(New Employee() With {.ID = 13, .ParentID = 3, .Name = "Sidney L. Holder", .Department = "Operations", .Position = "Manager"})

            stuff.Add(New Employee() With {.ID = 14, .ParentID = 4, .Name = "James L. Kelsey", .Department = "Production", .Position = "Manager"})
            stuff.Add(New Employee() With {.ID = 15, .ParentID = 4, .Name = "Howard M. Carpenter", .Department = "Production", .Position = "Manager"})
            stuff.Add(New Employee() With {.ID = 16, .ParentID = 4, .Name = "Jennifer T. Tapia", .Department = "Production", .Position = "Manager"})

            stuff.Add(New Employee() With {.ID = 17, .ParentID = 5, .Name = "Judith P. Underhill", .Department = "Finance", .Position = "Manager"})
            stuff.Add(New Employee() With {.ID = 18, .ParentID = 5, .Name = "Russell E. Belton", .Department = "Finance", .Position = "Manager"})
            Return stuff
        End Function
    End Class
End Namespace

MainWindow.xaml.cs

using System.Windows;
using DevExpress.Xpf.Grid;

namespace DXTreeList_NodeTraversing {
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window {
        public MainWindow() {
            InitializeComponent();
            treeListControl1.ItemsSource = Stuff.GetStuff();
        }

        private void treeListControl1_Loaded(object sender, RoutedEventArgs e) {
            SmartExpandNodes(4);
        }

        private void SmartExpandNodes(int minChildCount) {
            TreeListNodeIterator nodeIterator = new TreeListNodeIterator(treeListView1.Nodes, true);
            while (nodeIterator.MoveNext())
                nodeIterator.Current.IsExpanded = nodeIterator.Current.Nodes.Count >= minChildCount;
        }
    }
}

Employees.cs

using System;
using System.Collections.Generic;

namespace DXTreeList_NodeTraversing {

    public class Employee {
        public int ID { get; set; }
        public int ParentID { get; set; }
        public string Name { get; set; }
        public string Position { get; set; }
        public string Department { get; set; }
    }

    public static class Stuff {
        public static List<Employee> GetStuff() {
            List<Employee> stuff = new List<Employee>();
            stuff.Add(new Employee() { ID = 1, ParentID = 0, Name = "Gregory S. Price", Department = "", Position = "President" });
            stuff.Add(new Employee() { ID = 2, ParentID = 1, Name = "Irma R. Marshall", Department = "Marketing", Position = "Vice President" });
            stuff.Add(new Employee() { ID = 3, ParentID = 1, Name = "John C. Powell", Department = "Operations", Position = "Vice President" });
            stuff.Add(new Employee() { ID = 4, ParentID = 1, Name = "Christian P. Laclair", Department = "Production", Position = "Vice President" });
            stuff.Add(new Employee() { ID = 5, ParentID = 1, Name = "Karen J. Kelly", Department = "Finance", Position = "Vice President" });

            stuff.Add(new Employee() { ID = 6, ParentID = 2, Name = "Brian C. Cowling", Department = "Marketing", Position = "Manager" });
            stuff.Add(new Employee() { ID = 7, ParentID = 2, Name = "Thomas C. Dawson", Department = "Marketing", Position = "Manager" });
            stuff.Add(new Employee() { ID = 8, ParentID = 2, Name = "Angel M. Wilson", Department = "Marketing", Position = "Manager" });
            stuff.Add(new Employee() { ID = 9, ParentID = 2, Name = "Bryan R. Henderson", Department = "Marketing", Position = "Manager" });

            stuff.Add(new Employee() { ID = 10, ParentID = 3, Name = "Harold S. Brandes", Department = "Operations", Position = "Manager" });
            stuff.Add(new Employee() { ID = 11, ParentID = 3, Name = "Michael S. Blevins", Department = "Operations", Position = "Manager" });
            stuff.Add(new Employee() { ID = 12, ParentID = 3, Name = "Jan K. Sisk", Department = "Operations", Position = "Manager" });
            stuff.Add(new Employee() { ID = 13, ParentID = 3, Name = "Sidney L. Holder", Department = "Operations", Position = "Manager" });

            stuff.Add(new Employee() { ID = 14, ParentID = 4, Name = "James L. Kelsey", Department = "Production", Position = "Manager" });
            stuff.Add(new Employee() { ID = 15, ParentID = 4, Name = "Howard M. Carpenter", Department = "Production", Position = "Manager" });
            stuff.Add(new Employee() { ID = 16, ParentID = 4, Name = "Jennifer T. Tapia", Department = "Production", Position = "Manager" });

            stuff.Add(new Employee() { ID = 17, ParentID = 5, Name = "Judith P. Underhill", Department = "Finance", Position = "Manager" });
            stuff.Add(new Employee() { ID = 18, ParentID = 5, Name = "Russell E. Belton", Department = "Finance", Position = "Manager" });
            return stuff;
        }
    }
}