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GridControl.CustomGroupDisplayTextCommand Property

wpf-devexpress-dot-xpf-dot-grid-dot-gridcontrol-03ac8b03.md

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GridControl.CustomGroupDisplayTextCommand Property

Gets or sets a command that displays custom text in group rows.

Namespace : DevExpress.Xpf.Grid

Assembly : DevExpress.Xpf.Grid.v25.2.dll

NuGet Package : DevExpress.Wpf.Grid.Core

Declaration

csharp
public ICommand<GroupDisplayTextArgs> CustomGroupDisplayTextCommand { get; set; }
vb
Public Property CustomGroupDisplayTextCommand As ICommand(Of GroupDisplayTextArgs)

Property Value

TypeDescription
ICommand<GroupDisplayTextArgs>

A command that displays custom text in group rows.

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Remarks

Bind a command to the CustomGroupDisplayTextCommand property to maintain a clean MVVM pattern. The command works like a CustomGroupDisplayText event handler and allows you to specify custom group row text in a View Model.

You can use the GridControl.CustomColumnGroupCommand property to specify the command that applies custom rules to group rows. In this instance, it may be useful to replace the default text displayed in group rows. To do this, follow the steps below:

  1. Create a command that displays custom text in the group rows.
  2. In the command, use the GroupDisplayTextArgs.Value property to get the default group row text and assign your custom text to the GroupDisplayTextArgs.DisplayText property.
  3. Assign the command to the CustomGroupDisplayTextCommand 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

xaml
<dxg:GridControl ItemsSource="{Binding ListPerson}"
                 CustomColumnGroupCommand="{Binding CustomColumnGroupCommand}" 
                 CustomGroupDisplayTextCommand="{Binding CustomGroupDisplayTextCommand}">
    <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>
csharp
using DevExpress.Mvvm;
using DevExpress.Mvvm.DataAnnotations;
using DevExpress.Mvvm.Xpf;
// ...
public class MainViewModel : ViewModelBase {
// ...
    [Command]
    public void CustomColumnGroup(RowSortArgs args) {
        if(args.FieldName != "UnitPrice")
            return;
        double x = Math.Floor(Convert.ToDouble(args.FirstValue) / 10);
        double y = Math.Floor(Convert.ToDouble(args.SecondValue) / 10);
        args.Result = x > 9 && y > 9 ? 0 : x.CompareTo(y);
    }

    [Command]
    public void CustomGroupDisplayText(GroupDisplayTextArgs args) {
        if(args.FieldName != "UnitPrice")
            return;
        string interval = IntervalByValue(args.Value);
        args.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;
    }
}
vb
Imports DevExpress.Mvvm
Imports DevExpress.Mvvm.DataAnnotations
Imports DevExpress.Mvvm.Xpf
' ...
Public Class MainViewModel
    Inherits ViewModelBase
' ...
    <Command>
    Public Sub CustomColumnGroup(ByVal args As RowSortArgs)
        If Not Equals(args.FieldName, "UnitPrice") Then Return
        Dim x As Double = Math.Floor(Convert.ToDouble(args.FirstValue) / 10)
        Dim y As Double = Math.Floor(Convert.ToDouble(args.SecondValue) / 10)
        args.Result = If(x > 9 AndAlso y > 9, 0, x.CompareTo(y))
    End Sub

    <Command>
    Public Sub CustomGroupDisplayText(ByVal args As GroupDisplayTextArgs)
        If Not Equals(args.FieldName, "UnitPrice") Then Return
        Dim interval As String = IntervalByValue(args.Value)
        args.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
End Class

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

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.

wpf-data-grid-implement-custom-grouping/CS/CustomGrouping_MVVM/MainWindow.xaml#L14

xml
CustomColumnGroupCommand="{Binding CustomColumnGroupCommand}"
             CustomGroupDisplayTextCommand="{Binding CustomGroupDisplayTextCommand}">
<dxg:GridControl.Columns>

See Also

GridControl Class

GridControl Members

DevExpress.Xpf.Grid Namespace