GridView.CustomSummaryExists Event

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

Namespace: DevExpress.XtraGrid.Views.Grid

Assembly: DevExpress.XtraGrid.v24.2.dll

Declaration

C#

[DXCategory("Data")]
public event CustomSummaryExistEventHandler CustomSummaryExists

VB.NET

<DXCategory("Data")>
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. There are two cases depending on the summary type:

• A total summary value is about to be calculated. In this case, the CustomSummaryEventArgs.IsTotalSummary parameter returns true. You may read the CustomSummaryExistEventArgs.Item property to identify the summary item and, thus, identify the column where the summary will be displayed. If you need to prohibit calculating the summary value, set the CustomSummaryExistEventArgs.Exists parameter to false.
• A group summary value is about to be calculated. In this case, the CustomSummaryExistEventArgs.IsGroupSummary parameter returns true. Read the CustomSummaryExistEventArgs.GroupRowHandle parameter value to identify the group for which the summary value is about to be calculated. The CustomSummaryExistEventArgs.Item parameter identifies the summary item. If you don’t need this summary item to display its value within the current group, set the CustomSummaryExistEventArgs.Exists parameter to false.

The example below illustrates how to skip calculating summaries for a specific column.

C#

//Add a group "Count" summary
GridSummaryItem item1 = gridView1.GroupSummary.Add();
item1.SummaryType = DevExpress.Data.SummaryItemType.Count;
item1.Tag = 1;

//Add a group summary for the "Extended Price" column
GridSummaryItem item2 = gridView1.GroupSummary.Add();
item2.FieldName = "ExtendedPrice";
item2.SummaryType = DevExpress.Data.SummaryItemType.Sum;
item2.Tag = 2;
item2.DisplayFormat = "Sum={0:c2}";

// Do not calculate the Sum function (Tag=2) for City group rows  
private void gridView1_CustomSummaryExists(object sender, DevExpress.Data.CustomSummaryExistEventArgs e) {
    GridView view = sender as GridView;
    int summaryTag = Convert.ToInt32((e.Item as GridSummaryItem).Tag);
    GridColumn groupColumn = view.GroupedColumns[e.GroupLevel];
    if (groupColumn.FieldName == "City" && summaryTag == 2) {
        e.Exists = false;
    }
}

VB.NET

'Add a group "Count" summary
Private item1 As GridSummaryItem = gridView1.GroupSummary.Add()
item1.SummaryType = DevExpress.Data.SummaryItemType.Count
item1.Tag = 1

'Add a group summary for the "Extended Price" column
Dim item2 As GridSummaryItem = gridView1.GroupSummary.Add()
item2.FieldName = "ExtendedPrice"
item2.SummaryType = DevExpress.Data.SummaryItemType.Sum
item2.Tag = 2
item2.DisplayFormat = "Sum={0:c2}"

' Do not calculate the Sum function (Tag=2) for City group rows  
private void gridView1_CustomSummaryExists(Object sender, DevExpress.Data.CustomSummaryExistEventArgs e)
    Dim view As GridView = TryCast(sender, GridView)
    Dim summaryTag As Integer = Convert.ToInt32((TryCast(e.Item, GridSummaryItem)).Tag)
    Dim groupColumn As GridColumn = view.GroupedColumns(e.GroupLevel)
    If groupColumn.FieldName = "City" AndAlso summaryTag = 2 Then
        e.Exists = False
    End If

Example

By default, the Data Grid calculates group summaries (GridView.GroupSummary) for each group level. The following example handles the GridView.CustomSummaryExists event to allow a Count group summary to be only calculated for the root level and prevent it from being calculated for nested data groups.

The image below demonstrates the result.

C#

using DevExpress.XtraGrid;

private void gridView1_CustomSummaryExists(object sender, DevExpress.Data.CustomSummaryExistEventArgs e) {
    GridGroupSummaryItem item = e.Item as GridGroupSummaryItem;
    if (item == null) return;
    if (e.GroupLevel > 0 && item.SummaryType == DevExpress.Data.SummaryItemType.Count)
        e.Exists = false;
}

VB.NET

Imports DevExpress.XtraGrid

Private Sub GridView1_CustomSummaryExists(sender As Object, e As CustomSummaryExistEventArgs) Handles GridView1.CustomSummaryExists
    Dim item As GridGroupSummaryItem = TryCast(e.Item, GridGroupSummaryItem)
    If (item Is Nothing) Then Return
    If (e.GroupLevel > 0 AndAlso item.SummaryType = DevExpress.Data.SummaryItemType.Count) Then
        e.Exists = False
    End If
End Sub