Data items can be grouped by adding standard PropertyGroupDescription objects or DataGridGroupDescription objects (recommended) to the GroupDescriptions property of the DataGridCollectionViewSource or DataGridCollectionView to which a grid is bound, to a DataGridDetailDescription, and/or directly through the Items property and specifying the field name of the column by whose values to group. Each DataGridGroupDescription object that is added to this collection represents the characteristics of a group level in a grid.
Information about the groups that were added to a GroupDescriptions collection can also be retrieved through the GroupLevelDescriptions property of the DataGridControl, DataGridContext, or DetailConfiguration classes . The GroupLevelDescription objects contained in these collections provide complementary information on the group descriptions that were added through the GroupDescriptions property; however, they do not allow modifications to the group descriptions to be made (see Example 1).
Figure 1: Grouping in TableView |
 Figure 2: Grouping in CardView |
 |
The name of the property in the data item and the value of the FieldName property must be identical in order for grouping to work. |
Grouping at Runtime
By default, when a DataGridControl is created it contains a HierarhicalGroupByControl in its fixed headers section (see Figure 3). The group-by control provides a condensed view of the group levels and allows end users to modify the group descriptions applied to a grid. Each group level is represented by a HierarchicalGroupByItem that can be used to change the order of the groups, sort the data items, or remove the groups altogether. If a ColumnManagerRow (see Figure 4) is present in a grid (regardless of its location), its cells (ColumnManagerCell) can be dragged onto the group-by control to create an additional group level.
 Figure 3 |
 Figure 4 |
The AllowGroupingModification property indicates whether groups can be added or removed, by the end user, through a group-by control (see Example 2).
 |
This property only affects end-user interaction and does not prevent grouping from being modified programmatically. |
Examples
All examples in this topic assume that the grid is bound to the Orders table of the Northwind database, unless stated otherwise.
Example 1: Grouping data items
The following example demonstrates how to group the data items by the ShipCountry and ShipCity columns.
| 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>
<xcdg:DataGridControl x:Name="OrdersGrid"
ItemsSource="{Binding Source={StaticResource cvs_orders}}">
</xcdg:DataGridControl>
</Grid> |
Example 2: Preventing grouping and sorting
The following example demonstrates how to bind a grid to the Orders table and prevent columns from being sorted and reordered and groups from being created or removed. By default, the ShipCountry and ShipCity columns will be sorted, grouped, and fixed.
| XAML |
Copy Code |
<Grid xmlns:xcdg="http://schemas.xceed.com/wpf/xaml/datagrid"
xmlns:d="clr-namespace:System.Windows.Data;assembly=PresentationFramework"
xmlns:scm="clr-namespace:System.ComponentModel;assembly=WindowsBase">
<Grid.Resources>
<xcdg:DataGridCollectionViewSource x:Key="cvs_orders"
Source="{Binding Source={x:Static Application.Current},
Path=Orders}">
<xcdg:DataGridCollectionViewSource.SortDescriptions>
<scm:SortDescription PropertyName="ShipCountry" Direction="Ascending"/>
<scm:SortDescription PropertyName="ShipCity" Direction="Ascending"/>
</xcdg:DataGridCollectionViewSource.SortDescriptions>
<xcdg:DataGridCollectionViewSource.GroupDescriptions>
<xcdg:DataGridGroupDescription PropertyName="ShipCountry"/>
<xcdg:DataGridGroupDescription PropertyName="ShipCity"/>
</xcdg:DataGridCollectionViewSource.GroupDescriptions>
</xcdg:DataGridCollectionViewSource>
</Grid.Resources>
<xcdg:DataGridControl x:Name="OrdersGrid"
ItemsSource="{Binding Source={StaticResource cvs_orders}}">
<xcdg:DataGridControl.Columns>
<xcdg:Column FieldName="ShipCountry" VisiblePosition="0"/>
<xcdg:Column FieldName="ShipCity" VisiblePosition="1"/>
</xcdg:DataGridControl.Columns>
<xcdg:DataGridControl.View>
<xcdg:TableView FixedColumnCount="2" UseDefaultHeadersFooters="False">
<xcdg:TableView.FixedHeaders>
<DataTemplate>
<xcdg:GroupByControl AllowSort="False" AllowGroupingModification="False"/>
</DataTemplate>
<DataTemplate>
<xcdg:ColumnManagerRow AllowSort="False" AllowColumnReorder="False"/>
</DataTemplate>
</xcdg:TableView.FixedHeaders> </xcdg:TableView>
</xcdg:DataGridControl.View>
</xcdg:DataGridControl>
</Grid> |
Example 3: Custom grouping
This example demonstrates how to create a custom group description by deriving from the DataGridGroupDescription class and overriding the GroupNameFromItem method. The custom group description will group items according to the first letter in the value received as a parameter.
The implementation for the custom sort comparer assigned to the group description's SortComparer property is provided below.
| VB.NET |
Copy Code |
Imports System
Imports System.Collections.Generic
Imports System.Text
Imports Xceed.Wpf.DataGrid
Imports System.Collections
Imports System.Globalization;
Namespace Xceed.Wpf.Documentation
Public Class AlphabeticalGroupDescription
Inherits DataGridGroupDescription
Public Sub New()
MyBase.New()
End Sub
Public Sub New(ByVal propertyName As String)
MyBase.New(propertyName)
End Sub
Public Overrides Function GroupNameFromItem(ByVal item As Object, _
ByVal level As Integer, _
ByVal culture As CultureInfo) As Object
Dim value As Object = MyBase.GroupNameFromItem(item, level, culture)
Try
Dim content As String = Convert.ToString(value)
value = content.ToUpper().Substring(0, 1)
Catch e1 As InvalidCastException
End Try
Return value
End Function
End Class
End Namespace |
| C# |
Copy Code |
using System;
using System.Collections.Generic;
using System.Text;
using Xceed.Wpf.DataGrid;
using System.Collections;
namespace Xceed.Wpf.Documentation
{
public class AlphabeticalGroupDescription : DataGridGroupDescription {
public AlphabeticalGroupDescription()
: base()
{
}
public AlphabeticalGroupDescription( string propertyName )
: base( propertyName )
{
}
public override object GroupNameFromItem( object item, int level,
System.Globalization.CultureInfo culture )
{
object value = base.GroupNameFromItem( item, level, culture );
try
{ string content = Convert.ToString( value );
value = content.ToUpper().Substring( 0, 1 );
}
catch( InvalidCastException )
{
}
return value;
} }
} |
The following code demonstrates how to use the custom group description by adding it to the DataGridCollectionViewSource's GroupDescriptions property.
| XAML |
Copy Code |
<Grid.Resources>
<local:ConsonantVowelComparer x:Key="consonantVowelComparer"/>
<xcdg:DataGridCollectionViewSource x:Key="cvs_orders"
Source="{Binding
Source={x:Static Application.Current},
Path=Orders}">
<xcdg:DataGridCollectionViewSource.GroupDescriptions>
<local:AlphabeticalGroupDescription PropertyName="ShipCountry"
SortComparer="{StaticResource consonantVowelComparer}"/>
</xcdg:DataGridCollectionViewSource.GroupDescriptions> </xcdg:DataGridCollectionViewSource>
</Grid.Resources>
<xcdg:DataGridControl x:Name="OrdersGrid"
ItemsSource="{Binding Source={StaticResource cvs_orders}}"/>
</Grid>
|
The following code provides the implementation for the custom sort comparer that is used to sort, by vowels then consonants, the group descriptions create above.
| VB.NET |
Copy Code |
Imports System
Imports System.Collections.Generic
Imports System.Text
Imports System.Collections
Namespace Xceed.Wpf.Documentation
Public Class ConsonantVowelComparer
Public Sub New()
End Sub
Public Function Compare(ByVal x As Object, _
ByVal y As Object) As Integer Implements IComparer.Compare
If (TypeOf x Is String) AndAlso (TypeOf y Is String) Then
Dim xString As String = x.ToString().ToLowerInvariant()
Dim yString As String = y.ToString().ToLowerInvariant()
Dim isXVowel As Boolean = m_vowels.Contains(xString)
Dim isYVowel As Boolean = m_vowels.Contains(yString)
If isXVowel Xor isYVowel Then
If isXVowel Then
Return -1
Else
Return 1
End If
End If
Return String.Compare(xString, yString)
End If
Throw New ArgumentException()
Private Const m_vowels As String = "aeiouy"
End Class
End Namespace |
| C# |
Copy Code |
using System;
using System.Collections.Generic;
using System.Text;
using System.Collections;
namespace Xceed.Wpf.Documentation
{
public class ConsonantVowelComparer : IComparer
{
public ConsonantVowelComparer()
{
}
public int Compare( object x, object y )
{
if( ( x is string ) && ( y is string ) )
{
string xString = x.ToString().ToLowerInvariant();
string yString = y.ToString().ToLowerInvariant();
bool isXVowel = m_vowels.Contains( xString );
bool isYVowel = m_vowels.Contains( yString );
if( isXVowel ^ isYVowel )
return isXVowel ? -1 : 1;
return String.Compare( xString, yString );
}
throw new ArgumentException();
}
private const string m_vowels = "aeiouy";
}
} |
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