TreeListOperation.Execute Method

using DevExpress.XtraTreeList;

// declaring the custom operation class 
public class TreeListExceedLimitOperation : TreeListOperation {
   private string fieldName;
   private int upperLimit;
   private int result;

   public TreeListExceedLimitOperation(string fieldName, int upperLimit) {
      this.fieldName = fieldName;
      this.upperLimit = upperLimit;
      result = 0;
   }
   // incrementing the counter if the node's value exceeds the limit 
   public override void Execute(TreeListNode node) {
      int nodeValue = Convert.ToInt32(node[fieldName]);
      if (nodeValue > upperLimit)
         result++;
   }
   public int Result {
      get { return result; }
   }
}

// ... 
// using the created class to calculate the number of nodes 
// that have a value greater than 500000 in their Budget field 
private void treeList1_GetCustomSummaryValue(object sender, GetCustomSummaryValueEventArgs e) {
   if (e.IsSummaryFooter) {
      TreeListExceedLimitOperation operation = 
        new TreeListExceedLimitOperation("Budget", 500000);
      treeList1.NodesIterator.DoOperation(operation);
      e.CustomValue = operation.Result;
   }
}

Imports DevExpress.XtraTreeList

' declaring the custom operation class 
Public Class TreeListExceedLimitOperation
   Inherits TreeListOperation

   Private FieldName As String 
   Private UpperLimit As Integer 
   Private _result As Integer 

   Public Sub New(ByVal FieldName As String, ByVal UpperLimit As Integer)
      Me.FieldName = FieldName
      Me.UpperLimit = UpperLimit
      _result = 0
   End Sub 

   ' incrementing the counter if the node's value exceeds the limit 
   Public Overrides Sub Execute(ByVal Node As TreeListNode)
      Dim NodeValue As Integer = Convert.ToInt32(Node(FieldName))
      If NodeValue > UpperLimit Then _result += 1
   End Sub 

   Public ReadOnly Property Result() As Integer 
      Get 
         Return _result
      End Get 
   End Property 
End Class 

' ... 
' using the created class to calculate the number of nodes 
' that have a value greater than 500000 in their Budget field 
Private Sub TreeList1_GetCustomSummaryValue(ByVal sender As Object, _
ByVal e As GetCustomSummaryValueEventArgs) Handles TreeList1.GetCustomSummaryValue
   If (e.IsSummaryFooter) Then 
      Dim Operation As New TreeListExceedLimitOperation("Budget", 500000)
      TreeList1.NodesIterator.DoOperation(Operation)
      e.CustomValue = Operation.Result
   End If 
End Sub