ForeignKeyConverter Class

Represents a foreign key converter, which allows custom key/value mappings to be provided.

Syntax

Visual Basic
C#

'Declaration
 
Public MustInherit Class ForeignKeyConverter

'Usage
 
Dim instance As ForeignKeyConverter

public abstract class ForeignKeyConverter

Remarks

By default, foreign key constraints defined by a DataTable or DataView as well as enums can be automatically detected; however, through a ForeignKeyConverter, custom key/value mappings can also be defined. When providing custom key/value mappings, a foreign key converter must be created by deriving from the ForeignKeyConverter class and overriding its GetKeyFromValue and GetValueFromKey methods in which the value for a specified key and the key for a specified value should be returned (see implementation of PersonForeignKeyConverter class in Example 2). This converter can then be provided to the ForeignKeyConverter property of either a foreign key description or configuration.

If a ForeignKeyConverter has not been explicitly provided for a ForeignKeyConfiguration, the converter from its corresponding DataGridForeignKeyDescription will be used.

Example

The following code provides the implementation of the PersonForeignKeyConverter class. The following code provides the implementation of the PersonForeignKeyConverter class.

Visual Basic
C#

Public Class PersonForeignKeyConverter

             Inherits ForeignKeyConverter



  Public Overrides Function GetKeyFromValue( value As Object, configuration As ForeignKeyConfiguration ) As Object

    Dim bindingList As PersonBindingList = TryCast( configuration.ItemsSource, PersonBindingList )

    If Not bindingList Is Nothing Then

      Dim person As Person = TryCast( value, Person )

      If Not person Is Nothing Then

        Return person.PersonID

      End If

    End If

    Return -1

  End Function

  Public Overrides Function GetValueFromKey( key As Object, configuration As ForeignKeyConfiguration ) As Object

   Dim bindingList As PersonBindingList = TryCast( configuration.ItemsSource, PersonBindingList )

    If Not bindingList Is Nothing Then

      Try

        Dim personID As Integer = CInt( key )

        Dim person As Person

        For Each person In bindingList

          If person.PersonID = personID Then

            Return person

          End If

        Next person

      Catch e As Exception

        ' key can be nothing

      End Try

    Return Nothing

  End Function

End Class

public class PersonForeignKeyConverter : ForeignKeyConverter

{

 public override object GetKeyFromValue( object value, ForeignKeyConfiguration configuration )

 {

   PersonBindingList bindingList = configuration.ItemsSource as PersonBindingList;

   if( bindingList != null )

   {

     Person person = value as Person;

     if( person != null )

     {

       return person.PersonID;

     }

   }

   return -1;

 }

 public override object GetValueFromKey( object key, ForeignKeyConfiguration configuration )

 {

   PersonBindingList bindingList = configuration.ItemsSource as PersonBindingList;

   if( bindingList != null )

   {

     try

     {

       int personID = ( int )key;

       foreach( Person person in bindingList )

       {

         if( person.PersonID == personID )

         {

           return person;

         }

       }

     }

     catch( Exception )

     {

       // key can be null

     }

   }

   return null;

 }

}

Inheritance Hierarchy

System.Object
   Xceed.Wpf.DataGrid.ForeignKeyConverter
      Xceed.Wpf.DataGrid.DataGridForeignKeyConverter
      Xceed.Wpf.DataGrid.DataTableForeignKeyConverter

Requirements

Target Platforms: Windows 11, Windows 10, Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

ForeignKeyConverter Members
Xceed.Wpf.DataGrid Namespace