Infragistics(R) NetAdvantage(R) Windows Forms
GroupByEvaluator Property
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Infragistics.Win.UltraWinGrid Namespace > UltraGridColumn Class : GroupByEvaluator Property

Property used to perform non-default group by comparisons.

Syntax

Visual Basic (Declaration) 
Public Property GroupByEvaluator As IGroupByEvaluator
C# 
public IGroupByEvaluator GroupByEvaluator {get; set;}

Example

Following code shows you how to group rows with a custom group-by code. It groups rows by the first two characters of the company name field. It implements IGroupByEvaluator interface and assigns an instance of it to the GroupByEvaluator property of ContactName column and then groups rows by it.

Visual BasicCopy Code
Imports Infragistics.Shared
Imports Infragistics.Win
Imports Infragistics.Win.UltraWinGrid

  Public Class MyGroupByEvaluator
      Implements Infragistics.Win.UltraWinGrid.IGroupByEvaluator

      Private Function GetGroupByValue(ByVal groupbyRow As UltraGridGroupByRow, ByVal row As UltraGridRow) As Object Implements IGroupByEvaluator.GetGroupByValue

          Dim val As String

          ' Get the default value from the groupbyRow.
          If groupbyRow.Value Is Nothing Then
              val = ""
          Else
              val = groupbyRow.Value.ToString()
          End If

          ' If it is longer than 2 characters truncate it.
          If val.Length > 2 Then
              val = val.Substring(0, 2)
          End If

          ' Convert the string to uppercase for display in the group-by row's description.
          Return val.ToUpper()

      End Function

      Private Function DoesGroupContainRow(ByVal groupbyRow As UltraGridGroupByRow, ByVal row As UltraGridRow) As Boolean Implements IGroupByEvaluator.DoesGroupContainRow

          ' Get the related cell's value as a string.
          Dim cellValue As String = row.Cells(groupbyRow.Column).Value.ToString()

          ' If it is longer than 2 characters truncate it.
          If cellValue.Length > 2 Then
              cellValue = cellValue.Substring(0, 2)
          End If

          ' Do a case insensitive compare.
          Return 0 = String.Compare(groupbyRow.Value.ToString(), cellValue, True)
      End Function

  End Class

  Private Sub Button35_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles button35.Click

      ' Set the view style to OutlookGroupBy to enable the outlook-group-by feature.
      Me.UltraGrid1.DisplayLayout.ViewStyleBand = ViewStyleBand.OutlookGroupBy

      ' Get the CompanyName column.
      Dim column As UltraGridColumn = Me.UltraGrid1.DisplayLayout.Bands(0).Columns("CompanyName")

      ' Set the GroupByEvaluator on the column to an instance of MyGroupByEvaluator.
      column.GroupByEvaluator = New MyGroupByEvaluator()

      ' Set the column's HiddenWhenGroupBy property to false since we are
      ' grouping by the 1st 2 characters of each string we want the full
      ' company name to show in each row.
      column.HiddenWhenGroupBy = DefaultableBoolean.False

      ' Now group the rows by the column.
      Me.UltraGrid1.DisplayLayout.Bands(0).SortedColumns.Add(column, False, True)

  End Sub
C#Copy Code
using Infragistics.Shared;
using Infragistics.Win;
using Infragistics.Win.UltraWinGrid;
using System.Diagnostics;

public class MyGroupByEvaluator : Infragistics.Win.UltraWinGrid.IGroupByEvaluator
{
	public object GetGroupByValue( UltraGridGroupByRow groupbyRow, UltraGridRow row )
	{

		string val;
		
		// Get the default value from the groupbyRow.
		if (groupbyRow.Value == null )
			val = "";
		else
			val = groupbyRow.Value.ToString();
	
		// If it is longer than 2 characters truncate it.
		if ( val.Length > 2 )
			val = val.Substring( 0, 2 );
	
		// Convert the string to uppercase for display in the group-by row's description.
		return val.ToUpper();

	}
	
	public bool DoesGroupContainRow( UltraGridGroupByRow groupbyRow, UltraGridRow row )
	{

		// Get the related cell's value as a string.
		string cellValue = row.Cells[groupbyRow.Column].Value.ToString();
	
		// If it is longer than 2 characters truncate it.
		if ( cellValue.Length > 2 )
			cellValue = cellValue.Substring(0, 2);
	
		// Do a case insensitive compare.
		return 0 == string.Compare(groupbyRow.Value.ToString(), cellValue, true);
	}

}

private void button35_Click(object sender, System.EventArgs e)
{

	// Set the view style to OutlookGroupBy to enable the outlook-group-by feature.
	this.ultraGrid1.DisplayLayout.ViewStyleBand = ViewStyleBand.OutlookGroupBy;
	
	// Get the CompanyName column.
	UltraGridColumn column = this.ultraGrid1.DisplayLayout.Bands[0].Columns["CompanyName"];
	 
	// Set the GroupByEvaluator on the column to an instance of MyGroupByEvaluator 
	column.GroupByEvaluator = new MyGroupByEvaluator();
	 
	// Set the column's HiddenWhenGroupBy property to false since we are
	// grouping by the 1st 2 characters of each string we want the full
	// company name to show in each row.
	column.HiddenWhenGroupBy = DefaultableBoolean.False;

	// Now group the rows by the column.
	this.ultraGrid1.DisplayLayout.Bands[0].SortedColumns.Add( column, false, true );

}

Remarks

This GroupByEvaluator object will be used for determining which rows are included in group by rows. Essentially it lets you use custom logic for grouping rows.

Care should be taken to ensure that the GroupByEvaluator is logically consistent with the Infragistics.Win.UltraWinGrid.UltraGridColumn.SortComparer. For example, if the sort comparer does a case insensitive sort the group by evaluator logic should be case-insensitive as well. If your grouping logic requires that it be inconsistent with how the rows are sorted, then you need to implement IGroupByEvaluatorEx interface. IGroupByEvaluatorEx interface lets you supply logic for sorting rows for grouping purposes. See IGroupByEvaluatorEx interface for more information.

See Also