GridControl.CustomColumnGroup Event

Provides the capability to group data using custom rules.

Namespace: DevExpress.UI.Xaml.Grid

Assembly: DevExpress.UI.Xaml.Grid.v21.2.dll

NuGet Package: DevExpress.Uwp.Controls

Declaration

C#

public event CustomColumnSortEventHandler CustomColumnGroup

VB.NET

Public Event CustomColumnGroup As CustomColumnSortEventHandler

Event Data

The CustomColumnGroup event's data class is CustomColumnSortEventArgs. The following properties provide information specific to this event:

Property	Description
Column	Gets the column whose values are being compared.
Handled	Gets or sets whether a comparison operation is handled and no default processing is required.
ListSourceRowIndex1	Gets the index of the first of the two rows being compared in the data source.
ListSourceRowIndex2	Gets the index of the second of the two rows being compared in the data source.
Result	Gets or sets the result of a custom comparison.
SortOrder	Gets the sort order applied to the column.
Source	Gets the grid control that raised the event.
Value1	Gets the first value being compared.
Value2	Gets the second value being compared.

Remarks

If the built-in grouping modes don’t suit your requirements, you can implement custom logic. To do this, set the ColumnBase.SortMode property to ‘Custom’, and handle the CustomColumnGroup event. To change the text displayed within group rows by default, handle the GridControlBase.CustomGroupDisplayText event.

Example

This example shows how to group rows using custom rules. When grouping by the 'Unit Price' column, the rows in this column that have values between 0 and 10 should be combined into a single group. Rows whose values fall between 10 and 20 should be combined into another group, etc.

XAML

<Page
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:HowToCustomGrouping"
    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="HowToCustomGrouping.MainPage"
    mc:Ignorable="d">
    <Grid>
        <Grid:GridControl Name="grid" CustomColumnGroup="GridControl_CustomColumnGroup" CustomGroupDisplayText="GridControl_CustomGroupDisplayText" Background="Black" Foreground="White" >
            <Grid:GridControl.Columns>
                <Grid:GridTextColumn FieldName="ProductName" />
                <Grid:GridTextColumn FieldName="Supplier" />
                <Grid:GridTextColumn FieldName="UnitPrice" SortMode="Custom"/>
                <Grid:GridTextColumn FieldName="Quantity" />
            </Grid:GridControl.Columns>
        </Grid:GridControl>
    </Grid>
</Page>

C#

using System;
using System.Collections.Generic;
using Windows.UI.Xaml.Controls;

namespace HowToCustomGrouping
{
    public sealed partial class MainPage : Page
    {
        public MainPage()
        {
            this.InitializeComponent();
            grid.ItemsSource = new ProductList();
            grid.Columns["UnitPrice"].GroupIndex = 0;
        }

        private void GridControl_CustomColumnGroup(object sender, DevExpress.UI.Xaml.Grid.CustomColumnSortEventArgs e) {
            if (e.Column.FieldName == "UnitPrice") {
                double x = Math.Floor(Convert.ToDouble(e.Value1) / 10);
                double y = Math.Floor(Convert.ToDouble(e.Value2) / 10);
                int res = Comparer<double>.Default.Compare(x,y);
                if (x > 9 && y > 9) res = 0;
                e.Result = res;
                e.Handled = true;
            }
        }

        private void GridControl_CustomGroupDisplayText(object sender, DevExpress.UI.Xaml.Grid.CustomGroupDisplayTextEventArgs e) {
            if (e.Column.FieldName != "UnitPrice") return;
            string interval = IntervalByValue(e.Value);
            e.DisplayText = interval;

        }
        private string IntervalByValue(object val) {
            double d = Math.Floor(Convert.ToDouble(val) / 10);
            string ret = string.Format("{0:c} - {1:c} ", d * 10, (d + 1) * 10);
            if (d > 9) ret = string.Format(">= {0:c} ", 100);
            return ret;
        }

    }
}

VB.NET

Imports HowToCustomGrouping.Data

Public NotInheritable Class MainPage
    Inherits Page
    Public Sub New()
        InitializeComponent()
        grid.ItemsSource = New ProductList()
        grid.Columns("UnitPrice").GroupIndex = 0
    End Sub
    Private Sub GridControl_CustomColumnGroup(sender As Object, e As DevExpress.UI.Xaml.Grid.CustomColumnSortEventArgs)
        If e.Column.FieldName = "UnitPrice" Then
            Dim x As Double = Math.Floor(Convert.ToDouble(e.Value1) / 10)
            Dim y As Double = Math.Floor(Convert.ToDouble(e.Value2) / 10)
            Dim res As Integer = Comparer(Of Double).[Default].Compare(x, y)
            If x > 9 AndAlso y > 9 Then
                res = 0
            End If
            e.Result = res
            e.Handled = True
        End If
    End Sub

    Private Sub GridControl_CustomGroupDisplayText(sender As Object, e As DevExpress.UI.Xaml.Grid.CustomGroupDisplayTextEventArgs)
        If e.Column.FieldName <> "UnitPrice" Then
            Return
        End If
        Dim interval As String = IntervalByValue(e.Value)
        e.DisplayText = interval

    End Sub
    Private Function IntervalByValue(val As Object) As String
        Dim d As Double = Math.Floor(Convert.ToDouble(val) / 10)
        Dim ret As String = String.Format("{0:c} - {1:c} ", d * 10, (d + 1) * 10)
        If d > 9 Then
            ret = String.Format(">= {0:c} ", 100)
        End If
        Return ret
    End Function
End Class