Custom Detail Descriptions

The DataGridDetailDescription class provides information about a detail relation whose content will be displayed as the details of the data items in a grid or another detail. By default, detail descriptions are automatically created for:

• every DataRelation in a DataTable (DataRelationDetailDescription)
• data items that implement the IEnumerable interface (EnumerableDetailDescription)
• data items that implement the IListSource interface (ListSourceDetailDescription)
• every EntityCollection<TEntity> exposed by a data item (EntityDetailDescription)

Detail descriptions can also be explicitly defined by adding them to DetailDescriptions collection of their parent DataGridCollectionView, DataGridCollectionViewSource, or detail description.

Although the most common types of detail relations are automatically detected, it is also possible to create and use custom detail descriptions that will return detail items for a parent item, whatever the definition of the detail relation is.

Creating a Detail Description

Custom detail descriptions can be created by deriving from the DataGridDetailDescription class and overriding the GetDetailsForParentItem method to return the appropriate detail items, as an IEnumerable, for the received parent item (see Example 1). In the case where there are no detail items for a parent item, an empty IEnumerable or null (Nothing in Visual Basic) must be returned.

If a detail description requires information that cannot be provided through XAML, such as a PropertyDescriptor, the Initialize method can be overridden and the information provided.

Examples

All examples in this topic assume that the grid is bound to the Employees table of a LINQ data context, unless stated otherwise.

Example 1: Creating a custom detail description

The following example demonstrates how to create and use a custom detail description that handles LINQ detail relations, which are provided by properties to which the AssociationAttribute is applied.

XAML

<Grid>
  <Grid.Resources>
    <xcdg:DataGridCollectionViewSource x:Key="cvs_employees"
                                      Source="{Binding Source={x:Static Application.Current},
                                                        Path=LinqDataContext.Employees}">
      <xcdg:DataGridCollectionViewSource.DetailDescriptions>
          <local:LinqToSqlDetailDescription RelationName="Employee_Employees"
                                            Title="Employees" />
          <local:LinqToSqlDetailDescription RelationName="Employee_Customer"
                                            Title="Customers">
            <local:LinqToSqlDetailDescription.DetailDescriptions>
                <local:LinqToSqlDetailDescription RelationName="Customer_Order"
                                                  Title="Orders">
                  <local:LinqToSqlDetailDescription.DetailDescriptions>
                      <local:LinqToSqlDetailDescription RelationName="Order_Order_Detail"
                                                        Title="Order Details" />
                  </local:LinqToSqlDetailDescription.DetailDescriptions>
                </local:LinqToSqlDetailDescription>
            </local:LinqToSqlDetailDescription.DetailDescriptions>
          </local:LinqToSqlDetailDescription>
      </xcdg:DataGridCollectionViewSource.DetailDescriptions>
    </xcdg:DataGridCollectionViewSource>
  </Grid.Resources>

  <xcdg:DataGridControl x:Name="EmployeesGrid"
                      ItemsSource="{Binding Source={StaticResource cvs_employees}}"
                      ItemsSourceName="Employee Information"
                      AutoCreateDetailConfigurations="True" />
</Grid>

C#

  using System;
  using System.Collections.Generic;
  using System.Linq;
  using System.Text;
  using Xceed.Wpf.DataGrid;
  using System.Reflection;
  using System.Data.Linq.Mapping;
  using System.Diagnostics;
  using System.Collections;
  namespace Xceed.Wpf.Documentation
  {
    public class LinqToSqlDetailDescription: DataGridDetailDescription
    {
      protected override IEnumerable GetDetailsForParentItem( DataGridCollectionView parentCollectionView,
                                                              object parentItem )
      {
        Type parentItemType = parentItem.GetType();
        PropertyInfo foundProperty = null;
        
        PropertyInfo[] properties = parentItemType.GetProperties();
        foreach( PropertyInfo propertyInfo in properties )
        {
          object[] attributes = propertyInfo.GetCustomAttributes( typeof( AssociationAttribute ), false );
          if( attributes.GetLength( 0 ) == 0 )
            continue;
          AssociationAttribute associationAttribute = ( AssociationAttribute )attributes[ 0 ];
          if( associationAttribute.Name == this.RelationName )
          {
            foundProperty = propertyInfo;
            break;
          }
        }
        if( foundProperty == null )
        {
          return new object[] { };
        }
        else
        {
          object details = foundProperty.GetValue( parentItem, null );
          Type detailsType = details.GetType();
          MethodInfo getNewBindingList = detailsType.GetMethod( "GetNewBindingList" );
          return ( IEnumerable )getNewBindingList.Invoke( details, null );
        }
      }
    }
  }
  /*...*/
  NorthwindDataContext context = new NorthwindDataContext();      
  DataGridCollectionView collectionView = new DataGridCollectionView( context.Employees, typeof( Employee ), true, false );      
  collectionView.DetailDescriptions.Add( new LinqToSqlDetailDescription( "Employee_Employees", "Employees" ) );
  LinqToSqlDetailDescription employeeCustomerDetail = new LinqToSqlDetailDescription( "Employee_Customer", "Customers" );
  LinqToSqlDetailDescription customerOrderDetail = new LinqToSqlDetailDescription( "Customer_Order", "Orders" );
  customerOrderDetail.DetailDescriptions.Add( new LinqToSqlDetailDescription( "Order_Order_Detail", "Order Details" ) );
  employeeCustomerDetail.DetailDescriptions.Add( customerOrderDetail );
  collectionView.DetailDescriptions.Add( employeeCustomerDetail );
  dataGridControl.AutoCreateDetailConfigurations = true;
  dataGridControl.ItemsSourceName = "Employee Information";
  dataGridControl.ItemsSource = collectionView;

VB.NET

  Imports System
  Imports System.Collections.Generic
  Imports System.Linq
  Imports System.Text
  Imports Xceed.Wpf.DataGrid
  Imports System.Reflection
  Imports System.Data.Linq.Mapping
  Imports System.Diagnostics
  Imports System.Collections
  Namespace Xceed.Wpf.Documentation
    Public Class LinqToSqlDetailDescription
                Inherits DataGridDetailDescription
      Protected Overrides Function GetDetailsForParentItem( ByVal parentCollectionView As DataGridCollectionView, _
                                                            ByVal parentItem As Object ) As IEnumerable
        Dim parentItemType As Type = parentItem.GetType()
        Dim foundProperty As PropertyInfo = Nothing
        Dim properties() As PropertyInfo = parentItemType.GetProperties()
        Dim propertyInfo As PropertyInfo
        For Each propertyInfo In properties
          Dim attributes() As Object = propertyInfo.GetCustomAttributes( Type.GetType( AssociationAttribute ), _
                                                                          False)
          If attributes.GetLength( 0 ) = 0 Then
            continue
          End If
          Dim associationAttribute As AssociationAttribute = CType( attributes( 0 ), AssociationAttribute )
          If associationAttribute.Name = Me.RelationName Then
            foundProperty = propertyInfo
            Exit Property
          End If
        Next
        If foundProperty Is Nothing Then
          Return New Object()
        Else
          Dim details As Object = foundProperty.GetValue( parentItem, Nothing )
          Dim detailsType As Type = details.GetType()
          Dim getNewBindingList As MethodInfo = detailsType.GetMethod( "GetNewBindingList" )
          Return CType( getNewBindingList.Invoke( details, Nothing), IEnumerable )
        End If
      End Function
    End Class
  End Namespace
  `...
  Dim context As New NorthwindDataContext()
  Dim collectionView As New DataGridCollectionView( context.Employees, GetType( Employee ), True, False )
  collectionView.DetailDescriptions.Add( New LinqToSqlDetailDescription( "Employee_Employees", "Employees" ) )
  Dim employeeCustomerDetail As New LinqToSqlDetailDescription( "Employee_Customer", "Customers" )
  Dim customerOrderDetail As New LinqToSqlDetailDescription( "Customer_Order", "Orders" )
  customerOrderDetail.DetailDescriptions.Add( New LinqToSqlDetailDescription( "Order_Order_Detail", "Order Details" ) )
  employeeCustomerDetail.DetailDescriptions.Add( customerOrderDetail )
  collectionView.DetailDescriptions.Add( employeeCustomerDetail )
  dataGridControl.AutoCreateDetailConfigurations = True
  dataGridControl.ItemsSourceName = "Employee Information"
  dataGridControl.ItemsSource = collectionView