GridControl.CustomSummary Event

Enables you to calculate summary values manually.

Namespace: DevExpress.Xpf.Grid

Assembly: DevExpress.Xpf.Grid.v18.2.dll

Declaration

C#

public event CustomSummaryEventHandler CustomSummary

VB.NET

Public Event CustomSummary As CustomSummaryEventHandler

Event Data

The CustomSummary event's data class is CustomSummaryEventArgs. The following properties provide information specific to this event:

Property	Description
FieldValue	Gets the processed field value.
GroupLevel	Gets the nested level of the group whose summary value is being calculated.
GroupRowHandle	Gets a value identifying the group row whose child data rows are involved in summary calculation.
IsGroupSummary	Gets whether a group summary value is being calculated.
IsTotalSummary	Gets whether a total summary value is being calculated.
Item	Gets a summary item whose value is being calculated.
Row	Gets the currently processed row.
RowHandle	Gets the handle of the processed row.
SummaryProcess	Gets a value indicating calculation stage.
TotalValue	Gets or sets the total summary value.
TotalValueReady	Gets or sets whether the Calculation stage of the custom summary calculation process should be skipped.

The event data class exposes the following methods:

Method	Description
GetGroupSummary(Int32, Object)	Returns the value of the specified group summary for the specified group row.
GetValue(String)	Returns the value in the specified field

Remarks

Total summaries and group summaries provide five predefined aggregate functions (COUNT, MAX, MIN, SUM and AVG). If you want to calculate summaries using custom rules, handle the CustomSummary event. This event enables you to implement custom aggregate functions or calculate summary values, using a custom algorithm.

If the GridControl.View property is set to TreeListView, the CustomSummary event is not raised. Use the TreeListView.CustomSummary event instead.

Note

The CustomSummary event does not work in Server Mode.

To learn more, see Custom Summary.

Example

The following example demonstrates how to use custom summaries to count the total number of empty cells in the specified grid column.

Note

A complete sample project is available at https://github.com/DevExpress-Examples/how-to-summarize-empty-cells-e948.

Window1.xaml

<Window x:Class="CustomSummary_EmptyCells.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:dx="http://schemas.devexpress.com/winfx/2008/xaml/core"
    xmlns:dxg="http://schemas.devexpress.com/winfx/2008/xaml/grid"
    Title="Window1" Height="350" Width="450" >
    <Grid>
        <dxg:GridControl x:Name="grid" CustomSummary="grid_CustomSummary" GroupCount="1">
            <dxg:GridControl.SortInfo>
                <dxg:GridSortInfo FieldName="Text" />
            </dxg:GridControl.SortInfo>
            <dxg:GridControl.Columns>
                <dxg:GridColumn FieldName="Text" />
                <dxg:GridColumn FieldName="Number" />
            </dxg:GridControl.Columns>
            <dxg:GridControl.View>
                <dxg:TableView x:Name="view" AutoWidth="True" 
                                    NavigationStyle="Cell" ShowTotalSummary="True"/>
            </dxg:GridControl.View>
            <dxg:GridControl.TotalSummary>
                <dxg:GridSummaryItem FieldName="Number" SummaryType="Custom" 
                                    DisplayFormat="Total empty cells count: {0}"/>
            </dxg:GridControl.TotalSummary>
            <dxg:GridControl.GroupSummary>
                <dxg:GridSummaryItem FieldName="Number" SummaryType="Custom" 
                                    DisplayFormat="Group empty cells count: {0}"/>
            </dxg:GridControl.GroupSummary>
        </dxg:GridControl>
    </Grid>
</Window>

Window1.xaml.cs

using System.Windows;
using System.Collections.Generic;
using DevExpress.Data;
using DevExpress.Xpf.Data;
using DevExpress.Xpf.Grid;
// ...

namespace CustomSummary_EmptyCells {
    /// <summary>
    /// Interaction logic for Window1.xaml
    /// </summary>
    public partial class Window1 : Window {
        List<TestData> list;
        Dictionary<int, bool> selectedValues = new Dictionary<int, bool>();

        public Window1() {
            InitializeComponent();
            list = new List<TestData>();
            for (int i = 0; i < 100; i++) {
                list.Add(new TestData() { Text = "group " + i % 10, Number = i });
                if (i % 3 == 0)
                    list[i].Number = null;
            }
            grid.ItemsSource = list;
        }

        int emptyCellsTotalCount = 0;
        int emptyCellsGroupCount = 0;

        void grid_CustomSummary(object sender, CustomSummaryEventArgs e) {
            if (((GridSummaryItem)e.Item).FieldName != "Number")
                return;
            if (e.IsTotalSummary) {
                if (e.SummaryProcess == CustomSummaryProcess.Start) {
                    emptyCellsTotalCount = 0;
                }
                if (e.SummaryProcess == CustomSummaryProcess.Calculate) {
                    int? val = (int?)e.FieldValue;
                    if (!val.HasValue)
                        emptyCellsTotalCount++;
                    e.TotalValue = emptyCellsTotalCount;
                }
            }
            if (e.IsGroupSummary) {
                if (e.SummaryProcess == CustomSummaryProcess.Start) {
                    emptyCellsGroupCount = 0;
                }
                if (e.SummaryProcess == CustomSummaryProcess.Calculate) {
                    int? val = (int?)e.FieldValue;
                    if (!val.HasValue)
                        emptyCellsGroupCount++;
                    e.TotalValue = emptyCellsGroupCount;
                }
            }
        }

        public class TestData {
            public string Text { get; set; }
            public int? Number { get; set; }
        }
    }
}

Window1.xaml.vb

Imports Microsoft.VisualBasic
Imports System.Windows
Imports System.Collections.Generic
Imports DevExpress.Data
Imports DevExpress.Xpf.Data
Imports DevExpress.Xpf.Grid
' ...

Namespace CustomSummary_EmptyCells
    ''' <summary>
    ''' Interaction logic for Window1.xaml
    ''' </summary>
    Partial Public Class Window1
        Inherits Window
        Private list As List(Of TestData)
        Private selectedValues As New Dictionary(Of Integer, Boolean)()

        Public Sub New()
            InitializeComponent()
            list = New List(Of TestData)()
            For i As Integer = 0 To 99
                list.Add(New TestData() With {.Text = "group " & i Mod 10, .Number = i})
                If i Mod 3 = 0 Then
                    list(i).Number = Nothing
                End If
            Next i
            grid.ItemsSource = list
        End Sub

        Private emptyCellsTotalCount As Integer = 0
        Private emptyCellsGroupCount As Integer = 0

        Private Sub grid_CustomSummary(ByVal sender As Object, ByVal e As CustomSummaryEventArgs)
            If (CType(e.Item, GridSummaryItem)).FieldName <> "Number" Then
                Return
            End If
            If e.IsTotalSummary Then
                If e.SummaryProcess = CustomSummaryProcess.Start Then
                    emptyCellsTotalCount = 0
                End If
                If e.SummaryProcess = CustomSummaryProcess.Calculate Then
                    Dim val? As Integer = CType(e.FieldValue, Integer?)
                    If (Not val.HasValue) Then
                        emptyCellsTotalCount += 1
                    End If
                    e.TotalValue = emptyCellsTotalCount
                End If
            End If
            If e.IsGroupSummary Then
                If e.SummaryProcess = CustomSummaryProcess.Start Then
                    emptyCellsGroupCount = 0
                End If
                If e.SummaryProcess = CustomSummaryProcess.Calculate Then
                    Dim val? As Integer = CType(e.FieldValue, Integer?)
                    If (Not val.HasValue) Then
                        emptyCellsGroupCount += 1
                    End If
                    e.TotalValue = emptyCellsGroupCount
                End If
            End If
        End Sub

        Public Class TestData
            Private privateText As String
            Public Property Text() As String
                Get
                    Return privateText
                End Get
                Set(ByVal value As String)
                    privateText = value
                End Set
            End Property
            Private privateNumber? As Integer
            Public Property Number() As Integer?
                Get
                    Return privateNumber
                End Get
                Set(ByVal value? As Integer)
                    privateNumber = value
                End Set
            End Property
        End Class
    End Class
End Namespace

Related GitHub Examples

The following code snippet (auto-collected from DevExpress Examples) contains a reference to the CustomSummary event.

Note

The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.

C#

how-to-select-data-rows-e1666/CS/DXGrid_RowSelection/Window1.xaml#L35

</Grid.Resources>
<dxg:GridControl x:Name="grid" CustomSummary="grid_CustomSummary" CustomUnboundColumnData="grid_CustomUnboundColumnData">
    <dxg:GridControl.Columns>