How to: Summarize Empty Cells

• Jun 07, 2019
• 3 minutes to read

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

View Example

Window1.xaml

<Window x:Class="CustomSummary_EmptyCells.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:dx="http://schemas.devexpress.com/winfx/2008/xaml/core"
    xmlns:dxg="http://schemas.devexpress.com/winfx/2008/xaml/grid"
    Title="Window1" Height="350" Width="450" >
    <Grid>
        <dxg:GridControl x:Name="grid" CustomSummary="grid_CustomSummary" GroupCount="1">
            <dxg:GridControl.SortInfo>
                <dxg:GridSortInfo FieldName="Text" />
            </dxg:GridControl.SortInfo>
            <dxg:GridControl.Columns>
                <dxg:GridColumn FieldName="Text" />
                <dxg:GridColumn FieldName="Number" />
            </dxg:GridControl.Columns>
            <dxg:GridControl.View>
                <dxg:TableView x:Name="view" AutoWidth="True" 
                               NavigationStyle="Cell" ShowTotalSummary="True"/>
            </dxg:GridControl.View>
            <dxg:GridControl.TotalSummary>
                <dxg:GridSummaryItem FieldName="Number" SummaryType="Custom" 
                                     DisplayFormat="Total empty cells count: {0}"/>
            </dxg:GridControl.TotalSummary>
            <dxg:GridControl.GroupSummary>
                <dxg:GridSummaryItem FieldName="Number" SummaryType="Custom" 
                                     DisplayFormat="Group empty cells count: {0}"/>
            </dxg:GridControl.GroupSummary>
        </dxg:GridControl>
    </Grid>
</Window>

Window1.xaml.cs

using System.Windows;
using System.Collections.Generic;
using DevExpress.Data;
using DevExpress.Xpf.Data;
using DevExpress.Xpf.Grid;
// ...

namespace CustomSummary_EmptyCells {
    /// <summary>
    /// Interaction logic for Window1.xaml
    /// </summary>
    public partial class Window1 : Window {
        List<TestData> list;
        Dictionary<int, bool> selectedValues = new Dictionary<int, bool>();

        public Window1() {
            InitializeComponent();
            list = new List<TestData>();
            for (int i = 0; i < 100; i++) {
                list.Add(new TestData() { Text = "group " + i % 10, Number = i });
                if (i % 3 == 0)
                    list[i].Number = null;
            }
            grid.ItemsSource = list;
        }

        int emptyCellsTotalCount = 0;
        int emptyCellsGroupCount = 0;

        void grid_CustomSummary(object sender, 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;
                }
            }
            if (e.IsGroupSummary) {
                if (e.SummaryProcess == CustomSummaryProcess.Start) {
                    emptyCellsGroupCount = 0;
                }
                if (e.SummaryProcess == CustomSummaryProcess.Calculate) {
                    int? val = (int?)e.FieldValue;
                    if (!val.HasValue)
                        emptyCellsGroupCount++;
                    e.TotalValue = emptyCellsGroupCount;
                }
            }
        }

        public class TestData {
            public string Text { get; set; }
            public int? Number { get; set; }
        }
    }
}

Window1.xaml.vb

Imports Microsoft.VisualBasic
Imports System.Windows
Imports System.Collections.Generic
Imports DevExpress.Data
Imports DevExpress.Xpf.Data
Imports DevExpress.Xpf.Grid
' ...

Namespace CustomSummary_EmptyCells
    ''' <summary>
    ''' Interaction logic for Window1.xaml
    ''' </summary>
    Partial Public Class Window1
        Inherits Window
        Private list As List(Of TestData)
        Private selectedValues As New Dictionary(Of Integer, Boolean)()

        Public Sub New()
            InitializeComponent()
            list = New List(Of TestData)()
            For i As Integer = 0 To 99
                list.Add(New TestData() With {.Text = "group " & i Mod 10, .Number = i})
                If i Mod 3 = 0 Then
                    list(i).Number = Nothing
                End If
            Next i
            grid.ItemsSource = list
        End Sub

        Private emptyCellsTotalCount As Integer = 0
        Private emptyCellsGroupCount As Integer = 0

        Private Sub grid_CustomSummary(ByVal sender As Object, ByVal e As 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 Integer = CType(e.FieldValue, Integer?)
                    If (Not val.HasValue) Then
                        emptyCellsTotalCount += 1
                    End If
                    e.TotalValue = emptyCellsTotalCount
                End If
            End If
            If e.IsGroupSummary Then
                If e.SummaryProcess = CustomSummaryProcess.Start Then
                    emptyCellsGroupCount = 0
                End If
                If e.SummaryProcess = CustomSummaryProcess.Calculate Then
                    Dim val? As Integer = CType(e.FieldValue, Integer?)
                    If (Not val.HasValue) Then
                        emptyCellsGroupCount += 1
                    End If
                    e.TotalValue = emptyCellsGroupCount
                End If
            End If
        End Sub

        Public Class TestData
            Private privateText As String
            Public Property Text() As String
                Get
                    Return privateText
                End Get
                Set(ByVal value As String)
                    privateText = value
                End Set
            End Property
            Private privateNumber? As Integer
            Public Property Number() As Integer?
                Get
                    Return privateNumber
                End Get
                Set(ByVal value? As Integer)
                    privateNumber = value
                End Set
            End Property
        End Class
    End Class
End Namespace