GridView.CustomSummaryCalculate Event

Allows you to manually calculate summaries. Fires for summaries whose SummaryItemType.Custom is SummaryItemType.Custom.

Namespace: DevExpress.XtraGrid.Views.Grid

Assembly: DevExpress.XtraGrid.v20.1.dll

Declaration

[DXCategory("Data")]
public event CustomSummaryEventHandler CustomSummaryCalculate
<DXCategory("Data")>
Public Event CustomSummaryCalculate As CustomSummaryEventHandler

Event Data

The CustomSummaryCalculate 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.
Mode
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.

Remarks

If the GridSummaryItem.SummaryType property does not equal SummaryItemType.Custom, Data Grid automatically calculates summary values. Otherwise, the CustomSummaryCalculate event raises.

During the calculation process, the CustomSummaryCalculate event repeatedly fires multiple times.

In server mode, the CustomSummaryCalculate event fires only once (when the CustomSummaryProcess returns "Finalize"). Note that in this scenario the event does not fire for every row, and you can handle it to set the e.TotalValue parameter only.

gridView1.CustomSummaryCalculate += (obj, e) =>
{
    e.TotalValueReady = true;
    e.TotalValue = 100;
};

Refer to the Working with Summaries in Code. Custom Summaries topic for additional information.

Examples

The example below creates a new custom summary items and populates it on the GridView.CustomSummaryCalculate event. You can test this sample in our DevExpress Demo Center (the link requires Demo Center of version 16.2 or newer to be installed).

Grid - Custom Total Summary

The custom summary item is located under the "Length" column. To add it, set up the GridColumn.SummaryItem property.


gridView.OptionsView.ShowFooter = true;
GridColumn column = gridView.Columns["Length"];
column.SummaryItem.SummaryType = SummaryItemType.Custom;

The CustomSummaryCalculate event handler checks the current calculation state by reading the CustomSummaryEventArgs.SummaryProcess value. Cell values are added to the total sum only if the corresponding cell under the "Mark" column is checked.


double sum = 0;
gridView.CustomSummaryCalculate += (sender, e) => {
    GridView view = sender as GridView;
    if (e.IsTotalSummary && (e.Item as GridSummaryItem).FieldName=="Length") {
        GridSummaryItem item = e.Item as GridSummaryItem;
        if (item.FieldName == "Length") {
            switch (e.SummaryProcess) {
                case CustomSummaryProcess.Start:
                    sum = 0;
                    break;
                case CustomSummaryProcess.Calculate:
                    bool shouldSum = (bool)view.GetRowCellValue(e.RowHandle, "Mark");
                    if (shouldSum) {
                        sum += (double)e.FieldValue;
                    }
                    break;
                case CustomSummaryProcess.Finalize:
                    e.TotalValue = sum;
                break;
            }
        }
    }
};

To automatically update the summary item when users check or clear the "Mark" column checkboxes, the GridView.UpdateTotalSummary method is called on the RepositoryItem.EditValueChanged event.


RepositoryItemCheckEdit edit = gridView.Columns["Mark"].RealColumnEdit as RepositoryItemCheckEdit;
edit.EditValueChanged += (sender, e) => {
    //Post an editor's value to a data source
    gridView.PostEditor();
    //Force calculation of the total summary
    gridView.UpdateTotalSummary();
};

The code below is a complete example code.

    // Handle this event to calculate summary values manually
    double sum = 0;
    gridView.CustomSummaryCalculate += (sender, e) => {
        GridView view = sender as GridView;
        if (e.IsTotalSummary && (e.Item as GridSummaryItem).FieldName=="Length") {
            GridSummaryItem item = e.Item as GridSummaryItem;
            if (item.FieldName == "Length") {
                switch (e.SummaryProcess) {
                    case CustomSummaryProcess.Start:
                        sum = 0;
                        break;
                    case CustomSummaryProcess.Calculate:
                        bool shouldSum = (bool)view.GetRowCellValue(e.RowHandle, "Mark");
                        if (shouldSum) {
                            sum += (double)e.FieldValue;
                        }
                        break;
                    case CustomSummaryProcess.Finalize:
                        e.TotalValue = sum;
                        break;
                }
            }
        }
    };

    gridView.OptionsView.ShowFooter = true;
    GridColumn column = gridView.Columns["Length"];
    column.SummaryItem.SummaryType = SummaryItemType.Custom;

    RepositoryItemCheckEdit edit = gridView.Columns["Mark"].RealColumnEdit as RepositoryItemCheckEdit;
    edit.EditValueChanged += (sender, e) => {
        //Post an editor's value to a data source
        gridView.PostEditor();
        //Force calculation of the total summary
        gridView.UpdateTotalSummary();
    };
See Also