Xceed Toolkit Plus for WPF v4.6 Documentation
Filtering Data
Welcome to Xceed Toolkit Plus for WPF v4.6 > DataGrid, ListBox, Chart, AvalonDock, and PropertyGrid > Datagrid control > Fundamentals > Manipulating Data > Filtering Data

Prerequisite Knowledge
Object Model Overview: DataGridCollectionView Class
DataGrid Fundamentals: Providing Data

The items that are displayed in a view can be limited to one or more filtering criteria using either the native CollectionView filtering or automatic filtering meaning that even if an item exists in the underlying data source, it is not necessarily displayed in the view.

Native CollectionView Filtering

The data items that are displayed in a grid can be filtered using the Filter property of the DataGridCollectionViewBase or the Filter event of the DataGridCollectionViewSourceBase to which it is bound (see Example 1).

To refilter the data items displayed in a view the Refresh method can be called on the ItemsSource.

VB.NET Copy Code
CType( Me.OrdersGrid.ItemsSource, DataGridCollectionView ).Refresh()
C# Copy Code
( ( DataGridCollectionView )this.OrdersGrid.ItemsSource ).Refresh();

Custom Distinct Values

By default, the values that are displayed in the auto-filter drop down represent the distinct values as they are extracted from the underlying data source; however, custom distinct values can be provided for one or more item properties rather than the originally extracted distinct values by handling their QueryDistinctValue event and returning the custom value (see Example 3).

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: Filtering data items (Filter Event)

The following example demonstrates how to filter the data items displayed in a grid using the Filter event. Only the data items whose ShipVia property value is "3" will be displayed in the grid.

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}"
                                       Filter="ShipViaFilter"/>
  </Grid.Resources>
  <xcdg:DataGridControl x:Name="OrdersGrid"
                        ItemsSource="{Binding Source={StaticResource cvs_orders}}"/>
</Grid>

The following code provides the implementation of the ShipViaFilter event. This code should be placed in the "code-behind" of your XAML page.

VB.NET
Copy Code 
Private Sub ShipViaFilter( sender As Object, e As FilterEventArgs )
  Dim value As Object = CType( e.Item, System.Data.DataRow )( "ShipVia" )
  If( Not value Is Nothing ) And ( Not value Is DBNull.Value ) Then
    If CInt( value ) = 3 Then
      e.Accepted = True
    Else
      e.Accepted = False
    End If
  End If
End Sub
C#
Copy Code 
private void ShipViaFilter( object sender, FilterEventArgs e )
{
  object value = ( ( System.Data.DataRow )e.Item )[ "ShipVia" ]; 
  if( ( value != null ) && ( value != DBNull.Value ) )
  {
    if( ( int )value == 3 )
    {
     e.Accepted = true;
    }
    else
    {
     e.Accepted = false;
    }
  }   
}

The next example demonstrates how to filter data items using the Filter predicate delegate.

VB.NET
Copy Code 
Dim view As New DataGridCollectionView( Orders )
view.Filter = New Predicate(Of Object)( ShipViaFilter )
dataGridControl.ItemsSource = view
Private Function ShipViaFilter( item As Object ) As Boolean
   Dim value As Object = TryCast( item, System.Data.DataRow )( "ShipVia" )
   If( Not value Is Nothing ) And ( value <> DBNull.Value )Then
     If CInt( value ) == 3 Then
       Return True
     End If
   End If
   Return false
End Function
C#
Copy Code 
DataGridCollectionView view = new DataGridCollectionView( Orders );
view.Filter = new Predicate<object>( ShipViaFilter );
dataGridControl.ItemsSource = view;

private bool ShipViaFilter( object item )
{
  object value = ( ( System.Data.DataRow )item )[ "ShipVia" ];
  if( ( value != null ) && ( value != DBNull.Value ) )
  {
    if( ( int )value == 3 )       
      return true;       
  }
  return false;
}

Example 2: Providing custom distinct values

The following example demonstrates how to provide custom distinct values that will display the only the month in columns that display DateTime values and that will filter according to a value range for a decimal column.

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}"
                                        AutoFilterMode="And"
                                        DefaultCalculateDistinctValues="False">
        <xcdg:DataGridCollectionViewSource.ItemProperties>
          <xcdg:DataGridItemProperty Name="OrderDate"
                                     QueryDistinctValue="DataGridItemProperty_QueryDistinctValue_Date"
                                     CalculateDistinctValues="True"/>
          <xcdg:DataGridItemProperty Name="RequiredDate"
                                     QueryDistinctValue="DataGridItemProperty_QueryDistinctValue_Date"
                                     CalculateDistinctValues="True" />
          <xcdg:DataGridItemProperty Name="ShippedDate"
                                     QueryDistinctValue="DataGridItemProperty_QueryDistinctValue_Date"
                                     CalculateDistinctValues="True" />
          <xcdg:DataGridItemProperty Name="Freight"
                                     QueryDistinctValue="DataGridItemProperty_QueryDistinctValue_Range"
                                     CalculateDistinctValues="True" />
        </xcdg:DataGridCollectionViewSource.ItemProperties>
     </xcdg:DataGridCollectionViewSource>
  
  </Grid.Resources>
  <xcdg:DataGridControl x:Name="OrdersGrid"
                        ItemsSource="{Binding Source={StaticResource cvs_orders}}"/>
</Grid>
VB.NET
Copy Code 
Private Sub DataGridItemProperty_QueryDistinctValue_Date( ByVal sender As Object, ByVal e As QueryDistinctValueEventArgs )
  If TypeOf e.DataSourceValue Is DateTime Then
    e.DistinctValue = CDate( e.DataSourceValue ).ToString( "MMMM" )
  End If
End Sub
Private Sub DataGridItemProperty_QueryDistinctValue_Range( ByVal sender As Object, ByVal e As QueryDistinctValueEventArgs )
  If TypeOf e.DataSourceValue Is Decimal Then
    Dim value As Decimal = CDec( e.DataSourceValue )
    If value <= 100 Then
      e.DistinctValue = "0 - 100"
    ElseIf( value > 100 And value <= 500 ) Then
      e.DistinctValue = "101 - 500"
    Else
      e.DistinctValue = "500+"
    End If
  End If
End Sub
C#
Copy Code 
private void DataGridItemProperty_QueryDistinctValue_Date( object sender, QueryDistinctValueEventArgs e )
{
 if( e.DataSourceValue is DateTime )
 {
   e.DistinctValue = ( ( DateTime )e.DataSourceValue ).ToString( "MMMM" );
 }
}
private void DataGridItemProperty_QueryDistinctValue_Range( object sender, QueryDistinctValueEventArgs e )
{
 if( e.DataSourceValue is decimal )
 {
   decimal value = ( decimal )e.DataSourceValue;
   if( value <= 100 )
   {
     e.DistinctValue = "0 - 100";
   }
   else if( value > 100 && value <= 500 )
   {
     e.DistinctValue = "101 - 500";
   }
   else
   {
     e.DistinctValue = "500+";
   }
 }
}
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