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Xceed Toolkit Plus for WPF v5.1 Documentation
Xceed.Wpf.DataGrid.Toolkit Assembly / Xceed.Wpf.DataGrid Namespace / ForeignKeyConverter Class
Example


In This Topic
    ForeignKeyConverter Class
    In This Topic

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

    Syntax
    '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. 
    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

    Public Methods
     NameDescription
    Public MethodGetKeyFromValueRetrieves the key for the specified value.  
    Public MethodGetValueFromKeyOverloaded. 

    Retrieves the value for the specified key.

     
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    Supported Frameworks

    .NET: net5.0, net5.0-windows, net6.0, net6.0-macos, net6.0-windows, net7.0, net7.0-macos, net7.0-windows, net8.0, net8.0-browser, net8.0-macos, net8.0-windows, net9.0, net9.0-browser, net9.0-macos, net9.0-windows, net10.0, net10.0-browser, net10.0-macos, net10.0-windows.

    .NET Framework: net40, net403, net45, net451, net452, net46, net461, net462, net463, net47, net471, net472, net48, net481.

    See Also

    Reference

    ForeignKeyConverter Members
    Xceed.Wpf.DataGrid Namespace

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