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SurrogateSelector Class

Assists formatters in selection of the serialization surrogate to delegate the serialization or deserialization process to.

Namespace:  System.Runtime.Serialization
Assembly:  mscorlib (in mscorlib.dll)

<ComVisibleAttribute(True)> _
Public Class SurrogateSelector _
	Implements ISurrogateSelector

The SurrogateSelector type exposes the following members.

Public methodSurrogateSelectorInitializes a new instance of the SurrogateSelector class.

Public methodAddSurrogateAdds a surrogate to the list of checked surrogates.
Public methodChainSelectorAdds the specified ISurrogateSelector that can handle a particular object type to the list of surrogates.
Public methodEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodGetNextSelectorReturns the next selector on the chain of selectors.
Public methodGetSurrogateReturns the surrogate for a particular type.
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodRemoveSurrogateRemoves the surrogate associated with a given type.
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)

A serialization surrogate gives the users an object that can handle the serialization requirements of a different object and can transform the serialized data if necessary.

The following code example shows how to make a serialization surrogate class that knows how to properly serialize or deserialize a class that is not itself serializable. In addition, this example also shows how to recover from a SerializationException.

Imports System
Imports System.IO
Imports System.Runtime.Serialization
Imports System.Runtime.Serialization.Formatters
Imports System.Runtime.Serialization.Formatters.Binary

' This class is not serializable.
Friend Class Employee
	Public name, address As String

	Public Sub New(ByVal name As String, ByVal address As String) = name
		Me.address = address
	End Sub
End Class

' This class can manually serialize an Employee object.
Friend NotInheritable Class EmployeeSerializationSurrogate
	Implements ISerializationSurrogate

	' Serialize the Employee object to save the object�s name and address fields.
	Public Sub GetObjectData(ByVal obj As Object, ByVal info As SerializationInfo, ByVal context As StreamingContext) Implements ISerializationSurrogate.GetObjectData

		Dim emp As Employee = CType(obj, Employee)
		info.AddValue("address", emp.address)
	End Sub

	' Deserialize the Employee object to set the object�s name and address fields.
	Public Function SetObjectData(ByVal obj As Object, ByVal info As SerializationInfo, ByVal context As StreamingContext, ByVal selector As ISurrogateSelector) As Object Implements ISerializationSurrogate.SetObjectData

		Dim emp As Employee = CType(obj, Employee) = info.GetString("name")
		emp.address = info.GetString("address")
		Return Nothing
	End Function
End Class

Public NotInheritable Class App
	Shared Sub Main()
		' This sample uses the BinaryFormatter.
		Dim formatter As IFormatter = New BinaryFormatter()

		' Create a MemoryStream that the object will be serialized into and deserialized from.
		Using stream As Stream = New MemoryStream()
			' Create a SurrogateSelector.
			Dim ss As New SurrogateSelector()

			' Tell the SurrogateSelector that Employee objects are serialized and deserialized 
			' using the EmployeeSerializationSurrogate object.
			ss.AddSurrogate(GetType(Employee), New StreamingContext(StreamingContextStates.All), New EmployeeSerializationSurrogate())

			' Associate the SurrogateSelector with the BinaryFormatter.
			formatter.SurrogateSelector = ss

				' Serialize an Employee object into the memory stream.
				formatter.Serialize(stream, New Employee("Jeff", "1 Microsoft Way"))
			Catch e As SerializationException
				Console.WriteLine("Serialization failed: {0}", e.Message)
			End Try

			' Rewind the MemoryStream.
			stream.Position = 0

				' Deserialize the Employee object from the memory stream.
				Dim emp As Employee = CType(formatter.Deserialize(stream), Employee)

				' Verify that it all worked.
				Console.WriteLine("Name = {0}, Address = {1}",, emp.address)
			Catch e As SerializationException
				Console.WriteLine("Deserialization failed: {0}", e.Message)
			End Try
		End Using
	End Sub
End Class

' This code produces the following output.
' Name = Jeff, Address = 1 Microsoft Way

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.