'Declaration Public Property ForeignKeyConverter As ForeignKeyConverter
'Usage Dim instance As DataGridForeignKeyDescription Dim value As ForeignKeyConverter instance.ForeignKeyConverter = value value = instance.ForeignKeyConverter
public ForeignKeyConverter ForeignKeyConverter {get; set;}
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.
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; } }
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