Custom Summary

• Aug 01, 2019
• 3 minutes to read

Total summaries and group summaries provide five predefined aggregate functions that allow you to calculate:

• the number of data rows;
• the maximum and minimum values;
• the sum and the average value.

ASPxGridView provides the ASPxGridBase.CustomSummaryCalculate event that enables you to implement a custom summary. For example, custom summaries allow you to calculate summaries against records that meet specific criteria and use multiple data fields in calculations.

Implement Custom Summary

Follow the steps below to implement a custom summary:

• Create a summary item and set its ASPxSummaryItemBase.SummaryType property to SummaryItemType.Custom.
• Handle the ASPxGridBase.CustomSummaryCalculate event to calculate the summary.

The ASPxGridBase.CustomSummaryCalculate event fires for grid data rows in the following cases:

• Calculate a total summary value: the grid raises this event for each data row.

• Calculate a group summary value: the grid raises this event for each data row in a group.

Note

Note that the grid raises the ASPxGridBase.CustomSummaryCalculate before and after a row is processed.

The summary calculation consists of three stages:

• Initialization

  The grid raises the ASPxGridBase.CustomSummaryCalculate event once at this stage. The SummaryProcess property value is Start. Use this stage to initialize a summary value (for example, reset internal counters).

• Calculation

  The grid raises the ASPxGridBase.CustomSummaryCalculate event multiple times at this stage - for each data row in a grid or in a group. The SummaryProcess property value is Calculate. Use this stage to calculate a summary value.

  You can set the TotalValueReady property to true at the Initialization stage to skip the Calculation stage and calculate a custom summary at the Initialization or Finalization stage.

• Finalization

  The grid raises the ASPxGridBase.CustomSummaryCalculate event once at this stage. The SummaryProcess property value is Finalize. Use this stage to assign the calculated summary value to the TotalValue property.

Example

ASPX

<dx:ASPxGridView ID="ASPxGridView1" runat="server" OnCustomCallback="ASPxGridView1_CustomCallback" AutoGenerateColumns="False" DataSourceID="SqlDataSource1" ClientInstanceName="grid" Theme="Office365" KeyFieldName="ProductID" OnCustomSummaryCalculate="ASPxGridView1_CustomSummaryCalculate">
    <Columns>
        <dx:GridViewCommandColumn SelectAllCheckboxMode="Page" ShowSelectCheckbox="True" VisibleIndex="0">
        </dx:GridViewCommandColumn>
        <dx:GridViewDataTextColumn FieldName="ProductID" VisibleIndex="1" ReadOnly="True">
            <EditFormSettings Visible="False" />
        </dx:GridViewDataTextColumn>
        <dx:GridViewDataTextColumn FieldName="ProductName" VisibleIndex="2">
        </dx:GridViewDataTextColumn>
        <dx:GridViewDataTextColumn FieldName="UnitPrice" VisibleIndex="3">
        </dx:GridViewDataTextColumn>
    </Columns>
    <Settings ShowFooter="true" />
    <TotalSummary>
        <dx:ASPxSummaryItem SummaryType="Custom" FieldName="UnitPrice" ShowInColumn="UnitPrice" DisplayFormat="Total price for selected products: {0:c}" ValueDisplayFormat="{0}:c" />
    </TotalSummary>
</dx:ASPxGridView>
<br /> <br />
<dx:ASPxButton ID="ASPxButton4" runat="server" Text="Refresh" AutoPostBack="false" Theme="Office365">
    <ClientSideEvents Click="OnClick" />
</dx:ASPxButton>

C#

protected void ASPxGridView1_CustomSummaryCalculate(object sender, DevExpress.Data.CustomSummaryEventArgs e)
{
    // Initialization. 
    if (e.SummaryProcess == DevExpress.Data.CustomSummaryProcess.Start)
        totalSum = 0;
    else
    // Calculation. 
    if (e.SummaryProcess == DevExpress.Data.CustomSummaryProcess.Calculate)
    {
        if (ASPxGridView1.Selection.IsRowSelectedByKey(e.GetValue(ASPxGridView1.KeyFieldName)))
            totalSum += Convert.ToInt32(e.FieldValue);
    }
    else
    // Finalization. 
    if (e.SummaryProcess == DevExpress.Data.CustomSummaryProcess.Finalize)
        e.TotalValue = totalSum;
}
protected void ASPxGridView1_CustomCallback(object sender, DevExpress.Web.ASPxGridViewCustomCallbackEventArgs e)
{
    if (e.Parameters == "Refresh")
        ASPxGridView1.DataBind();
}

JS

function OnClick(s, e) {
    grid.PerformCallback('Refresh');
}

Result:

Online Demo

ASPxGridView - Export Selected Records