GridControl.GroupRowCollapsing Event

Occurs when a group row is about to be collapsed, allowing cancellation of the action.

Namespace: DevExpress.Xpf.Grid

Assembly: DevExpress.Xpf.Grid.v20.2.dll

NuGet Packages: DevExpress.WindowsDesktop.Wpf.Grid.Core, DevExpress.Wpf.Grid.Core

Declaration

C#

public event RowAllowEventHandler GroupRowCollapsing

VB.NET

Public Event GroupRowCollapsing As RowAllowEventHandler

Event Data

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

Property	Description
Allow	Gets or sets whether the operation is allowed.
Handled	Gets or sets a value that indicates the present state of the event handling for a routed event as it travels the route. Inherited from RoutedEventArgs.
OriginalSource	Gets the original reporting source as determined by pure hit testing, before any possible Source adjustment by a parent class. Inherited from RoutedEventArgs.
RoutedEvent	Gets or sets the RoutedEvent associated with this RoutedEventArgs instance. Inherited from RoutedEventArgs.
Row	Gets the processed row. Inherited from RowEventArgs.
RowHandle	Gets the processed row’s handle. Inherited from RowEventArgs.
Source	Gets or sets a reference to the object that raised the event. Inherited from RoutedEventArgs.

The event data class exposes the following methods:

Method	Description
InvokeEventHandler(Delegate, Object)	When overridden in a derived class, provides a way to invoke event handlers in a type-specific way, which can increase efficiency over the base implementation. Inherited from RoutedEventArgs.
OnSetSource(Object)	When overridden in a derived class, provides a notification callback entry point whenever the value of the Source property of an instance changes. Inherited from RoutedEventArgs.

Remarks

The GroupRowCollapsing event is raised before a group row is collapsed by an end-user or in code, allowing you to cancel this action. The group row is identified by its handle via the RowEventArgs.RowHandle property. To prevent the group row from being collapsed, set the event parameter’s RowAllowEventArgs.Allow parameter to false.

Group rows can be collapsed recursively using the GridViewBase.CollapseFocusedRow method overload with the recursive parameter set to true. In this instance, the GroupRowCollapsing event is raised only once (for the row passed as this method’s parameter). This event isn’t raised for nesting group rows.

The GridControl.CollapseAllGroups method allows you to collapse all group rows. In this instance, the GroupRowCollapsing event is raised only once. The event parameter’s RowEventArgs.RowHandle property returns an invalid row handle (DataControlBase.InvalidRowHandle).

After the group row has been collapsed, the GridControl.GroupRowCollapsed event is raised.

To learn more, see Expanding and Collapsing Group Rows.

Example

The following example shows how to customize whether a particular group row can be collapsed.In this example, the 'Status: Invalidated' group row is prevented from being collapsed, and the full collapsing is disabled. To do this, the GroupRowCollapsing event is handled, and the event parameter's Allow property is set to false when the RowHandle property returns the 'Status: Invalidated' row's handle, or an invalid handle (this happens when all group rows are about to be collapsed).

View Example

DataSource.cs

using System;
using System.Collections.Generic;

namespace DXExample.DemoData {
    public enum InvoiceStatus { Ordered, Payed, Shipped, Delivered, Invalidated }
    public class Invoice {
        public int ID { get; set; }
        public string ProductName { get; set; }
        public double Price { get; set; }
        public DateTime OrderDate { get; set; }
        public double Discount { get; set; }
        public bool IsUrgent { get; set; }
        public InvoiceStatus Status { get; set; }
        static public List<Invoice> GetData() {
            List<Invoice> data = new List<Invoice>();

            data.Add(new Invoice() { ID = 0, ProductName = "Tofu", IsUrgent = false,
                Price = 235.54, Discount = 9.4, Status = InvoiceStatus.Invalidated,
                OrderDate = new DateTime(2009, 3, 12) });
            data.Add(new Invoice() { ID = 1, ProductName = "Ravioli Angelo", IsUrgent = true,
                Price = 178.45, Discount = 6.1, Status = InvoiceStatus.Delivered,
                OrderDate = new DateTime(2009, 2, 9) });
            data.Add(new Invoice() { ID = 2, ProductName = "Geitost", IsUrgent = false,
                Price = 89.98, Discount = 5.4, Status = InvoiceStatus.Payed,
                OrderDate = new DateTime(2009, 4, 1) });
            data.Add(new Invoice() { ID = 3, ProductName = "Chang", IsUrgent = true,
                Price = 189.33, Discount = 18.2, Status = InvoiceStatus.Shipped,
                OrderDate = new DateTime(2009, 5, 23) });
            data.Add(new Invoice() { ID = 4, ProductName = "Inlagd Sill", IsUrgent = false, 
                Price = 509.10, Discount = 22.2, Status = InvoiceStatus.Ordered,
                OrderDate = new DateTime(2009, 6, 30) });
            data.Add(new Invoice() { ID = 5, ProductName = "Alice Mutton", IsUrgent = true,
                Price = 791.18, Discount = 24.4, Status = InvoiceStatus.Invalidated,
                OrderDate = new DateTime(2009, 5, 7) });

            return data;
        }
    }
}

Window1.xaml

<Window x:Class="DXGrid_PreventGroupRowFromCollapsing.Window1" 
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
        xmlns:dxg="http://schemas.devexpress.com/winfx/2008/xaml/grid"
        Title="Preventing Groups from Collapsing" Height="380" Width="335">
    <Grid>
        <dxg:GridControl
            GroupRowCollapsing="gridControl1_GroupRowCollapsing" AutoExpandAllGroups="True" Name="gridControl1">
            <dxg:GridControl.Columns>
                <dxg:GridColumn FieldName="ProductName" />
                <dxg:GridColumn FieldName="Price" Width="60" />
                <dxg:GridColumn FieldName="Discount" Width="75" />
                <dxg:GridColumn FieldName="Status" GroupIndex="0" SortOrder="Descending" x:Name="colStatus" />
            </dxg:GridControl.Columns>
            <dxg:GridControl.View>
                <dxg:TableView />
            </dxg:GridControl.View>
        </dxg:GridControl>
    </Grid>
</Window>

Window1.xaml.cs

using System.Windows;
using DevExpress.Xpf.Grid;
using DXExample.DemoData;

namespace DXGrid_PreventGroupRowFromCollapsing {
    public partial class Window1 : Window {
        public Window1() {
            InitializeComponent();
            gridControl1.ItemsSource = Invoice.GetData();
        }
        private void gridControl1_GroupRowCollapsing(object sender, RowAllowEventArgs e) {
            if (e.Row == null || ((Invoice)e.Row).Status == InvoiceStatus.Invalidated && colStatus.GroupIndex != -1)
                e.Allow = false;
        }
    }
}

Window1.xaml.vb

Imports System.Windows
Imports DevExpress.Xpf.Grid
Imports DXExample.DemoData

Namespace DXGrid_PreventGroupRowFromCollapsing
    Partial Public Class Window1
        Inherits Window

        Public Sub New()
            InitializeComponent()
            gridControl1.ItemsSource = Invoice.GetData()
        End Sub
        Private Sub gridControl1_GroupRowCollapsing(ByVal sender As Object, ByVal e As RowAllowEventArgs)
            If e.Row Is Nothing OrElse CType(e.Row, Invoice).Status = InvoiceStatus.Invalidated AndAlso colStatus.GroupIndex <> -1 Then
                e.Allow = False
            End If
        End Sub
    End Class
End Namespace

DataSource.vb

Imports System
Imports System.Collections.Generic

Namespace DXExample.DemoData
    Public Enum InvoiceStatus
        Ordered
        Payed
        Shipped
        Delivered
        Invalidated
    End Enum
    Public Class Invoice
        Public Property ID() As Integer
        Public Property ProductName() As String
        Public Property Price() As Double
        Public Property OrderDate() As Date
        Public Property Discount() As Double
        Public Property IsUrgent() As Boolean
        Public Property Status() As InvoiceStatus
        Public Shared Function GetData() As List(Of Invoice)
            Dim data As New List(Of Invoice)()

            data.Add(New Invoice() With {.ID = 0, .ProductName = "Tofu", .IsUrgent = False, .Price = 235.54, .Discount = 9.4, .Status = InvoiceStatus.Invalidated, .OrderDate = New Date(2009, 3, 12)})
            data.Add(New Invoice() With {.ID = 1, .ProductName = "Ravioli Angelo", .IsUrgent = True, .Price = 178.45, .Discount = 6.1, .Status = InvoiceStatus.Delivered, .OrderDate = New Date(2009, 2, 9)})
            data.Add(New Invoice() With {.ID = 2, .ProductName = "Geitost", .IsUrgent = False, .Price = 89.98, .Discount = 5.4, .Status = InvoiceStatus.Payed, .OrderDate = New Date(2009, 4, 1)})
            data.Add(New Invoice() With {.ID = 3, .ProductName = "Chang", .IsUrgent = True, .Price = 189.33, .Discount = 18.2, .Status = InvoiceStatus.Shipped, .OrderDate = New Date(2009, 5, 23)})
            data.Add(New Invoice() With {.ID = 4, .ProductName = "Inlagd Sill", .IsUrgent = False, .Price = 509.10, .Discount = 22.2, .Status = InvoiceStatus.Ordered, .OrderDate = New Date(2009, 6, 30)})
            data.Add(New Invoice() With {.ID = 5, .ProductName = "Alice Mutton", .IsUrgent = True, .Price = 791.18, .Discount = 24.4, .Status = InvoiceStatus.Invalidated, .OrderDate = New Date(2009, 5, 7)})

            Return data
        End Function
    End Class
End Namespace

Related GitHub Examples

The following code snippet (auto-collected from DevExpress Examples) contains a reference to the GroupRowCollapsing 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-grid-prevent-expand-collapse-operations-for-group-rows/CS/DXGrid_PreventGroupRowFromCollapsing/Window1.xaml#L8

<dxg:GridControl
    GroupRowCollapsing="gridControl1_GroupRowCollapsing" AutoExpandAllGroups="True" Name="gridControl1">
    <dxg:GridControl.Columns>