Items and Containers

Every item that is contained in a grid or detail has a container that provides it with a visual representation. Although normally a container's item is dealt with directly, sometimes it is necessary to access the container instead.

Through the GetContainerFromItem method, which is defined on both the DataGridControl and DataGridContext classes, the containers of data items (DataRow) and of any item located in the headers or footers of a grid or group, such as ColumnManagerRows, can be retrieved (see Examples 1 and 3).

Conversely, an item can be retrieved from its container using the GetItemFromContainer method, which is also defined on the DataGridControl and DataGridContext classes..

Only items that are visible in the viewport have containers. If GetContainerFromItem is called for an item that exists in the context but is not visible in the viewport, null (Nothing in Visual Basic) will be returned.

Group Items

A container that is located in the headers or footers of a group can be identified through the use of a GroupHeaderFooterItem, which is created from the CollectionViewGroup in which the container is located and the template that was used to create it. The GroupHeaderFooterItem structure can then be passed to the GetContainerFromItem method to retrieve the desired container. Through the GetParentGroupFromItem method, which is defined on both the DataGridControl and DataGridContext classes, the parent group of a data item or any GroupHeaderFooterItem structure, which also exposes its parent group through its Group property, can be retrieved. The newly retrieved group can then, for example, be expanded or collapsed using the ExpandGroup, CollapseGroup, or ToggleGroupExpansion methods (see Example 2).

Examples

All examples in this topic assume that the grid is bound to the Orders table of the Northwind database, unless stated otherwise.

The following example demonstrates how to select all the data items contained in a group by adding them to a grid's selected-items collection when a group-header control is pressed. In the case where a group contains child groups, all the data items in the child groups will also be selected.

XAML	Copy Code
<Grid xmlns:xcdg="http://schemas.xceed.com/wpf/xaml/datagrid"> <Grid.Resources> <xcdg:DataGridCollectionViewSource x:Key="cvs_orders" Source="{Binding Source={x:Static Application.Current}, Path=Orders}"> <xcdg:DataGridCollectionViewSource.GroupDescriptions> <xcdg:DataGridGroupDescription PropertyName="ShipCountry"/> <xcdg:DataGridGroupDescription PropertyName="ShipCity"/> </xcdg:DataGridCollectionViewSource.GroupDescriptions> </xcdg:DataGridCollectionViewSource> <Style TargetType="{x:Type xcdg:GroupHeaderControl}"> <EventSetter Event="PreviewMouseLeftButtonDown" Handler="SelectRows"/> </Style> </Grid.Resources> <xcdg:DataGridControl x:Name="OrdersGrid" ItemsSource="{Binding Source={StaticResource cvs_orders}}"/> </Grid>

XAML

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  <Grid xmlns:xcdg="http://schemas.xceed.com/wpf/xaml/datagrid">

    <Grid.Resources>

      <xcdg:DataGridCollectionViewSource x:Key="cvs_orders"

                                    Source="{Binding Source={x:Static Application.Current},

                                                        Path=Orders}">

        <xcdg:DataGridCollectionViewSource.GroupDescriptions>

          <xcdg:DataGridGroupDescription PropertyName="ShipCountry"/>

          <xcdg:DataGridGroupDescription PropertyName="ShipCity"/>

        </xcdg:DataGridCollectionViewSource.GroupDescriptions>

      </xcdg:DataGridCollectionViewSource>

    <Style TargetType="{x:Type xcdg:GroupHeaderControl}">

      <EventSetter Event="PreviewMouseLeftButtonDown"

                   Handler="SelectRows"/>

    </Style>

  </Grid.Resources>

    <xcdg:DataGridControl x:Name="OrdersGrid"

                        ItemsSource="{Binding Source={StaticResource cvs_orders}}"/>

  </Grid>

VB.NET	Copy Code
Private Sub SelectRows( ByVal sender As Object, ByVal e As MouseButtonEventArgs ) Dim groupHeaderControl As GroupHeaderControl = TryCast( sender, GroupHeaderControl ); If groupHeaderControl Is Nothing Then Return; End If Dim context As DataGridContext = DataGridControl.GetDataGridContext( groupHeaderControl ) Dim header As GroupHeaderFooterItem = TryCast( context.GetItemFromContainer( grouHeaderControl, GroupHeaderFooterItem ) If Not header.Equals( GroupHeaderFooterItem.Empty ) Then Dim group As CollectionViewGroup = context.GetParentGroupFromItem( header ) If Not group Is Nothing Then For Each item As Object In group.Items If TypeOf item Is CollectionViewGroup Then Me.SelectRecurse( context, CType( item, CollectionViewGroup ) ) Else context.SelectedItems.Add( item ) End If Next item End If End If End Sub Private Sub SelectRecurse( ByVal context As DataGridContext, ByVal group As CollectionViewGroup ) For Each item As Object In group.Items If TypeOf item Is CollectionViewGroup Then Me.SelectRecurse( context, CType( item, CollectionViewGroup ) ) Else context.SelectedItems.Add( item ) End If Next item End Sub

VB.NET

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Private Sub SelectRows( ByVal sender As Object, ByVal e As MouseButtonEventArgs )

  Dim groupHeaderControl As GroupHeaderControl = TryCast( sender, GroupHeaderControl );

  If groupHeaderControl Is Nothing Then

    Return;

  End If

  Dim context As DataGridContext = DataGridControl.GetDataGridContext( groupHeaderControl )

  Dim header As GroupHeaderFooterItem = TryCast( context.GetItemFromContainer( grouHeaderControl, GroupHeaderFooterItem )

  If Not header.Equals( GroupHeaderFooterItem.Empty ) Then

    Dim group As CollectionViewGroup = context.GetParentGroupFromItem( header )

    If Not group Is Nothing Then

      For Each item As Object In group.Items

        If TypeOf item Is CollectionViewGroup Then

          Me.SelectRecurse( context, CType( item, CollectionViewGroup ) )

        Else

          context.SelectedItems.Add( item )

        End If

      Next item

    End If

  End If

End Sub

Private Sub SelectRecurse( ByVal context As DataGridContext, ByVal group As CollectionViewGroup )

  For Each item As Object In group.Items

    If TypeOf item Is CollectionViewGroup Then

      Me.SelectRecurse( context, CType( item, CollectionViewGroup ) )

    Else

      context.SelectedItems.Add( item )

    End If

  Next item

End Sub

C#	Copy Code
private void SelectRows( object sender, MouseEventArgs e ) { GroupHeaderControl groupHeaderControl = sender as GroupHeaderControl; if( groupHeaderControl == null ) return; DataGridContext context = DataGridControl.GetDataGridContext( groupHeaderControl ); GroupHeaderFooterItem header = ( GroupHeaderFooterItem )context.GetItemFromContainer( groupHeaderControl ); if( !header.Equals( GroupHeaderFooterItem.Empty ) ) { CollectionViewGroup group = context.GetParentGroupFromItem( header ); if( group != null ) { foreach( object item in group.Items ) { if( item is CollectionViewGroup ) { this.SelectRecurse( context, ( CollectionViewGroup )item ); } else { context.SelectedItems.Add( item ); } } } } } private void SelectRecurse( DataGridContext context, CollectionViewGroup group ) { foreach( object item in group.Items ) { if( item is CollectionViewGroup ) { this.SelectRecurse( context, ( CollectionViewGroup )item ); } else { context.SelectedItems.Add( item ); } } }

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private void SelectRows( object sender, MouseEventArgs e )

{

GroupHeaderControl groupHeaderControl = sender as GroupHeaderControl;

if( groupHeaderControl == null )

  return;

DataGridContext context = DataGridControl.GetDataGridContext( groupHeaderControl );

GroupHeaderFooterItem header = ( GroupHeaderFooterItem )context.GetItemFromContainer( groupHeaderControl );

if( !header.Equals( GroupHeaderFooterItem.Empty ) )

{

  CollectionViewGroup group = context.GetParentGroupFromItem( header );

  if( group != null )

  {

    foreach( object item in group.Items )

    {

      if( item is CollectionViewGroup )

      {

        this.SelectRecurse( context, ( CollectionViewGroup )item );

      }

      else

      {

        context.SelectedItems.Add( item );

      }

    }

  }

}

}

private void SelectRecurse( DataGridContext context, CollectionViewGroup group )

{

foreach( object item in group.Items )

{

  if( item is CollectionViewGroup )

  {

    this.SelectRecurse( context, ( CollectionViewGroup )item );

  }

  else

  {

    context.SelectedItems.Add( item );

  }

}

}

The following example demonstrates how to retrieve the parent group of the current item using the GetParentGroupFromItem method so that it can be collapsed. The implementation for the CollapseCurrentGroup method is provided below.

XAML	Copy Code
<Grid xmlns:xcdg="http://schemas.xceed.com/wpf/xaml/datagrid"> <Grid.Resources> <xcdg:DataGridCollectionViewSource x:Key="cvs_orders" Source="{Binding Source={x:Static Application.Current}, Path=Orders}"> <xcdg:DataGridCollectionViewSource.GroupDescriptions> <xcdg:DataGridGroupDescription PropertyName="ShipCountry"/> <xcdg:DataGridGroupDescription PropertyName="ShipCity"/> </xcdg:DataGridCollectionViewSource.GroupDescriptions> </xcdg:DataGridCollectionViewSource> </Grid.Resources> <DockPanel> <Button Content="Collapse Group" Click="CollapseCurrentGroup" DockPanel.Dock="Top"/> <xcdg:DataGridControl x:Name="OrdersGrid" ItemsSource="{Binding Source={StaticResource cvs_orders}}" DockPanel.Dock="Bottom"/> </DockPanel> </Grid>

XAML

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<Grid xmlns:xcdg="http://schemas.xceed.com/wpf/xaml/datagrid">

  <Grid.Resources>

    <xcdg:DataGridCollectionViewSource x:Key="cvs_orders"

                                     Source="{Binding Source={x:Static Application.Current},

                                                      Path=Orders}">

      <xcdg:DataGridCollectionViewSource.GroupDescriptions>

        <xcdg:DataGridGroupDescription PropertyName="ShipCountry"/>

        <xcdg:DataGridGroupDescription PropertyName="ShipCity"/>

      </xcdg:DataGridCollectionViewSource.GroupDescriptions>

    </xcdg:DataGridCollectionViewSource>

  </Grid.Resources>

  <DockPanel>

    <Button Content="Collapse Group"

             Click="CollapseCurrentGroup"

            DockPanel.Dock="Top"/>

    <xcdg:DataGridControl x:Name="OrdersGrid"

                          ItemsSource="{Binding Source={StaticResource cvs_orders}}"

                          DockPanel.Dock="Bottom"/>

  </DockPanel>

</Grid>

The following provides the implementation for the CollapseCurrentGroup method.

VB.NET	Copy Code
Private Sub CollapseCurrentGroup( ByVal sender As Object, ByVal e As RoutedEventArgs ) Dim context As DataGridContext = Me.OrdersGrid.CurrentContext Dim group As CollectionViewGroup = context.GetParentGroupFromItem( context.CurrentItem ) context.CollapseGroup( group ) End Sub

VB.NET

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Private Sub CollapseCurrentGroup( ByVal sender As Object, ByVal e As RoutedEventArgs )

  Dim context As DataGridContext = Me.OrdersGrid.CurrentContext

  Dim group As CollectionViewGroup = context.GetParentGroupFromItem( context.CurrentItem )

  context.CollapseGroup( group )

End Sub

C#	Copy Code
private void CollapseCurrentGroup( object sender, RoutedEventArgs e ) { DataGridContext context = this.OrdersGrid.CurrentContext; CollectionViewGroup group = context.GetParentGroupFromItem( context.CurrentItem ); context.CollapseGroup( group ); }

Copy Code

private void CollapseCurrentGroup( object sender, RoutedEventArgs e )

{

  DataGridContext context = this.OrdersGrid.CurrentContext;

  CollectionViewGroup group = context.GetParentGroupFromItem( context.CurrentItem );

  context.CollapseGroup( group );

}

The following example demonstrates how to retrieve a DataRow (container) for a data item using the GetContainerFromItem method. It is important to remember that data rows are virtualized; therefore, references to them or their cells should never be kept.

VB.NET	Copy Code
Public Sub New() InitializeComponent() Dim grid As New DataGridControl() Dim view As New DataGridCollectionView( App.Orders.DefaultView ) grid.ItemsSource = view ' Subscribe to the PropertyChanged event to know when the CurrentItem property changes. AddHandler grid.PropertyChanged, AddressOf grid_PropertyChanged Me.Content = grid End Sub Private Sub grid_PropertyChanged( ByVal sender As Object, _ ByVal e As System.ComponentModel.PropertyChangedEventArgs ) If e.PropertyName = "CurrentItem" Then ' Retrieve the data-row container for the current item. Can be Nothing if the data item ' is not in the viewport. Dim grid As DataGridControl = CType( sender, DataGridControl ) Dim row As Xceed.Wpf.DataGrid.DataRow = TryCast( grid.GetContainerFromItem( grid.CurrentItem ), Xceed.Wpf.DataGrid.DataRow ) ' Change the background of the data row to pink. Data rows are recycled once they ' exit the viewport; therefore, any modifications made to a data row will ' be discarded once it is no longer in the viewport. row.Background = Brushes.Pink End If End Sub

VB.NET

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Public Sub New()

  InitializeComponent()

  Dim grid As New DataGridControl()

  Dim view As New DataGridCollectionView( App.Orders.DefaultView )

  grid.ItemsSource = view

  ' Subscribe to the PropertyChanged event to know when the CurrentItem property changes.

  AddHandler grid.PropertyChanged, AddressOf grid_PropertyChanged

  Me.Content = grid

End Sub

Private Sub grid_PropertyChanged( ByVal sender As Object, _

                                 ByVal e As System.ComponentModel.PropertyChangedEventArgs )

  If e.PropertyName = "CurrentItem" Then

    ' Retrieve the data-row container for the current item. Can be Nothing if the data item

    ' is not in the viewport.

    Dim grid As DataGridControl = CType( sender, DataGridControl )

    Dim row As Xceed.Wpf.DataGrid.DataRow = TryCast( grid.GetContainerFromItem( grid.CurrentItem ), Xceed.Wpf.DataGrid.DataRow )

    ' Change the background of the data row to pink. Data rows are recycled once they

    ' exit the viewport; therefore, any modifications made to a data row will

    ' be discarded once it is no longer in the viewport.

    row.Background = Brushes.Pink

  End If

End Sub

C#	Copy Code
public Window1() { InitializeComponent(); DataGridControl grid = new DataGridControl(); DataGridCollectionView view = new DataGridCollectionView( App.Orders.DefaultView ); grid.ItemsSource = view; // Subscribe to the PropertyChanged event to know when the CurrentItem property changes. grid.PropertyChanged += new System.ComponentModel.PropertyChangedEventHandler( grid_PropertyChanged ); this.Content = grid; } void grid_PropertyChanged( object sender, System.ComponentModel.PropertyChangedEventArgs e ) { if( e.PropertyName == "CurrentItem" ) { // Retrieve the data-row container for the current item. Can be null if the data item // is not in the viewport. DataGridControl grid = sender as DataGridControl; Xceed.Wpf.DataGrid.DataRow row = grid.GetContainerFromItem( grid.CurrentItem ) as Xceed.Wpf.DataGrid.DataRow; // Change the background of the data row to pink. Data rows are recycled once they // exit the viewport; therefore, any modifications made to a data row will // be discarded once it is no longer in the viewport. row.Background = Brushes.Pink; } }

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public Window1()

{

  InitializeComponent();

  DataGridControl grid = new DataGridControl();   

    

  DataGridCollectionView view = new DataGridCollectionView( App.Orders.DefaultView );

  grid.ItemsSource = view;

  // Subscribe to the PropertyChanged event to know when the CurrentItem property changes.

  grid.PropertyChanged +=

        new System.ComponentModel.PropertyChangedEventHandler( grid_PropertyChanged );    

    

  this.Content = grid;

}

void grid_PropertyChanged( object sender, System.ComponentModel.PropertyChangedEventArgs e )

{

  if( e.PropertyName == "CurrentItem" )

  {

    // Retrieve the data-row container for the current item. Can be null if the data item

    // is not in the viewport.

    DataGridControl grid = sender as DataGridControl;

    Xceed.Wpf.DataGrid.DataRow row = grid.GetContainerFromItem( grid.CurrentItem ) as Xceed.Wpf.DataGrid.DataRow;

    // Change the background of the data row to pink. Data rows are recycled once they

    // exit the viewport; therefore, any modifications made to a data row will

    // be discarded once it is no longer in the viewport.

    row.Background = Brushes.Pink;

  }

}

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