How to: Summarize Empty Cells

• Jul 26, 2018
• 2 minutes to read

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

XAML

<Page
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:CustomSummary"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:Grid="using:DevExpress.UI.Xaml.Grid"
    x:Class="CustomSummary.MainPage"
    mc:Ignorable="d">
    <Grid>
        <Grid:GridControl Name="grid"
                          AutoGenerateColumns="True"
                          ShowTotalSummary="True"
                          CustomSummary="grid_CustomSummary">
            <Grid:GridControl.TotalSummary>
                <Grid:GridSummaryItem FieldName="Number" SummaryType="Custom"
                                      DisplayFormat="Total empty cells count: {0}"/>
            </Grid:GridControl.TotalSummary>
        </Grid:GridControl>
    </Grid>
</Page>

C#

using System.Collections.Generic;
using DevExpress.Data;
using DevExpress.UI.Xaml.Grid;
using Windows.UI.Xaml.Controls;

namespace CustomSummary {
    public sealed partial class MainPage : Page {

        int emptyCellsTotalCount = 0;

        private void grid_CustomSummary(object sender, DevExpress.Data.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;
                }
            }
        }
    }
}

VB.NET

Imports DevExpress.UI.Xaml.Grid
Imports DevExpress.Data

Public NotInheritable Class MainPage
    Inherits Page

    Private emptyCellsTotalCount As Integer = 0

    Private Sub grid_CustomSummary(ByVal sender As Object, ByVal e As DevExpress.Data.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 Nullable(Of Integer) = CType(e.FieldValue, Nullable(Of Integer))
                If (Not val.HasValue) Then
                    emptyCellsTotalCount += 1
                End If
                e.TotalValue = emptyCellsTotalCount
            End If
        End If
    End Sub
End Class