GridControl.CustomSummaryExists Event

Enables you to specify which summaries should be calculated and displayed.

Namespace: DevExpress.Xpf.Grid

Assembly: DevExpress.Xpf.Grid.v23.2.dll

NuGet Package: DevExpress.Wpf.Grid.Core

Declaration

C#

public event CustomSummaryExistEventHandler CustomSummaryExists

VB.NET

Public Event CustomSummaryExists As CustomSummaryExistEventHandler

Event Data

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

Property	Description
Exists	Gets or sets whether the summary value should be calculated and displayed.
GroupLevel	Gets the nesting level of the group whose summary value is being calculated.
GroupRowHandle	Gets a value identifying the group row whose summary value is about to be calculated.
IsGroupSummary	Gets whether a group summary value is about to be calculated.
IsTotalSummary	Gets whether a total summary value is about to be calculated.
Item	Gets a summary item whose value is about to be calculated.

Remarks

The event is raised before a particular summary value is calculated, allowing cancellation of the calculation. To cancel summary value calculation, set the event parameter’s CustomSummaryExistEventArgs.Exists parameter to false.

• Total Summary

  In this case, the CustomSummaryExistEventArgs.IsTotalSummary parameter returns true. The processed summary item is returned by the CustomSummaryExistEventArgs.Item property. If required, use the summary item’s properties to identify the column where it is displayed.

• Group Summary

  In this case, the CustomSummaryExistEventArgs.IsGroupSummary parameter returns true. The CustomSummaryExistEventArgs.GroupRowHandle property identifies the group for which the summary value should be calculated. The processed group summary item is returned by the CustomSummaryExistEventArgs.Item property.

Note

The CustomSummaryExists event does not work in Server Mode.

If you want to maintain a clean MVVM pattern and specify whether to calculate a particular summary value in a View Model, create a command and bind it to the CustomSummaryExistsCommand property.

Example

The following example shows how to calculate group summaries and display them within group rows. A group summary is a value of the aggregate function calculated over all data rows within a group. The GridControl‘s GroupSummary collection stores group summary items.

This example uses the GridControl.CustomSummaryExists event to calculate group summaries only for the top group level:

View Example: How to Display Group Summaries

MainWindow.xaml

<dxg:GridControl x:Name="grid" CustomSummaryExists="OnCustomSummaryExists">
    <dxg:GridControl.View>
        <dxg:TableView AutoWidth="True"/>
    </dxg:GridControl.View>
    <dxg:GridControl.Columns>
        <dxg:GridColumn FieldName="UserName" />
        <dxg:GridColumn FieldName="RegistrationDate" />
        <dxg:GridColumn FieldName="Married" GroupIndex="0" SortOrder="Ascending" />
        <dxg:GridColumn FieldName="Age" />
    </dxg:GridControl.Columns>
    <dxg:GridControl.GroupSummary>
        <dxg:GridSummaryItem FieldName="Age" SummaryType="Min"/>
        <dxg:GridSummaryItem FieldName="Age" SummaryType="Max"/>
    </dxg:GridControl.GroupSummary>
</dxg:GridControl>

MainWindow.xaml.cs

void OnCustomSummaryExists(object sender, CustomSummaryExistEventArgs e) {
    e.Exists = e.GroupLevel == 0;
}

MainWindow.xaml.vb

Private Sub OnCustomSummaryExists(ByVal sender As Object, ByVal e As CustomSummaryExistEventArgs)
    e.Exists = e.GroupLevel = 0
End Sub

Related GitHub Examples

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

XAML

wpf-data-grid-display-group-summaries/CS/DisplayGroupSummaries_CodeBehind/MainWindow.xaml#L8

<Grid>
    <dxg:GridControl x:Name="grid" CustomSummaryExists="OnCustomSummaryExists">
        <dxg:GridControl.View>