GridControl.CustomColumnGroup Event

Allows you to create custom rules to group data.

Namespace: DevExpress.Xpf.Grid

Assembly: DevExpress.Xpf.Grid.v23.2.dll

NuGet Package: DevExpress.Wpf.Grid.Core

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.
Row1
Row2
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

To create custom rules instead of the built-in grouping modes:

1. Set the ColumnBase.SortMode property to Custom.
2. Handle the CustomColumnGroup event.

To change the text displayed in group rows, handle the GridControl.CustomGroupDisplayText event.

Note

The CustomColumnGroup event does not work in Server Mode.

If you want to maintain a clean MVVM pattern and specify custom group operations in a View Model, create a command and bind it to the CustomColumnGroupCommand property.

Example

The following example shows how to apply custom rules to group rows. When you group data by the Unit Price column, rows in this column that have values between 0 and 10 are combined into a single group. Rows whose values fall between 10 and 20 are combined into another group, and so forth.

View Example: How to Apply Custom Rules to Group Rows

MainWindow.xaml

<dxg:GridControl x:Name="grid" 
                 CustomColumnGroup="OnCustomColumnGroup" 
                 CustomGroupDisplayText="OnCustomGroupDisplayText">
    <dxg:GridControl.Columns>
        <dxg:GridColumn FieldName="FirstName" />
        <dxg:GridColumn FieldName="LastName" />
        <dxg:GridColumn FieldName="UnitPrice" SortMode="Custom" GroupIndex="0">
            <dxg:GridColumn.EditSettings>
                <dxe:SpinEditSettings DisplayFormat="c2" />
            </dxg:GridColumn.EditSettings>
        </dxg:GridColumn>
    </dxg:GridControl.Columns>
    <dxg:GridControl.View>
        <dxg:TableView AutoWidth="True" ShowGroupedColumns="True"/>
    </dxg:GridControl.View>
</dxg:GridControl>

MainWindow.xaml.cs

void OnCustomColumnGroup(object sender, CustomColumnSortEventArgs e) {
    if(e.Column.FieldName != "UnitPrice")
        return;
    double x = Math.Floor(Convert.ToDouble(e.Value1) / 10);
    double y = Math.Floor(Convert.ToDouble(e.Value2) / 10);
    e.Result = x > 9 && y > 9 ? 0 : x.CompareTo(y);
    e.Handled = true;
}

void OnCustomGroupDisplayText(object sender, CustomGroupDisplayTextEventArgs e) {
    if(e.Column.FieldName != "UnitPrice")
        return;
    string interval = IntervalByValue(e.Value);
    e.DisplayText = interval;
}

// Gets the interval which contains the specified value.
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;
}

MainWindow.xaml.vb

Private Sub OnCustomColumnGroup(ByVal sender As Object, ByVal e As CustomColumnSortEventArgs)
    If Not Equals(e.Column.FieldName, "UnitPrice") Then Return
    Dim x As Double = Math.Floor(Convert.ToDouble(e.Value1) / 10)
    Dim y As Double = Math.Floor(Convert.ToDouble(e.Value2) / 10)
    e.Result = If(x > 9 AndAlso y > 9, 0, x.CompareTo(y))
    e.Handled = True
End Sub

Private Sub OnCustomGroupDisplayText(ByVal sender As Object, ByVal e As CustomGroupDisplayTextEventArgs)
    If Not Equals(e.Column.FieldName, "UnitPrice") Then Return
    Dim interval As String = IntervalByValue(e.Value)
    e.DisplayText = interval
End Sub

' Gets the interval which contains the specified value.
Private Function IntervalByValue(ByVal 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)
    Return ret
End Function

Related GitHub Examples

The following code snippet (auto-collected from DevExpress Examples) contains a reference to the CustomColumnGroup event.

Note

The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.

XAML

wpf-data-grid-implement-custom-grouping/CS/CustomGrouping_CodeBehind/MainWindow.xaml#L10

<dxg:GridControl x:Name="grid"
                 CustomColumnGroup="OnCustomColumnGroup"
                 CustomGroupDisplayText="OnCustomGroupDisplayText">