SurrogateSelector Class
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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)

public class SurrogateSelector : ISurrogateSelector


Initializes a new instance of the SurrogateSelector class.

System_CAPS_pubmethodAddSurrogate(Type, StreamingContext, ISerializationSurrogate)

Adds a surrogate to the list of checked surrogates.


Adds the specified ISurrogateSelector that can handle a particular object type to the list of surrogates.


Determines whether the specified object is equal to the current object.(Inherited from Object.)


Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)


Serves as the default hash function. (Inherited from Object.)


Returns the next selector on the chain of selectors.

System_CAPS_pubmethodGetSurrogate(Type, StreamingContext, ISurrogateSelector)

Returns the surrogate for a particular type.


Gets the Type of the current instance.(Inherited from Object.)


Creates a shallow copy of the current Object.(Inherited from Object.)

System_CAPS_pubmethodRemoveSurrogate(Type, StreamingContext)

Removes the surrogate associated with a given type.


Returns 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.

Legacy Code Example

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.

using System;
using System.IO;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Formatters;
using System.Runtime.Serialization.Formatters.Binary;

// This class is not serializable.
class Employee 
    public String name, address;

    public Employee(String name, String address) 
    { = name;
        this.address = address;

// This class can manually serialize an Employee object.
sealed class EmployeeSerializationSurrogate : ISerializationSurrogate 

    // Serialize the Employee object to save the object�s name and address fields.
    public void GetObjectData(Object obj, 
        SerializationInfo info, StreamingContext context) 

        Employee emp = (Employee) obj;
        info.AddValue("address", emp.address);

    // Deserialize the Employee object to set the object�s name and address fields.
    public Object SetObjectData(Object obj,
        SerializationInfo info, StreamingContext context,
        ISurrogateSelector selector) 

        Employee emp = (Employee) obj; = info.GetString("name");
        emp.address = info.GetString("address");
        return null;

public sealed class App 
    static void Main() 
        // This sample uses the BinaryFormatter.
        IFormatter formatter = new BinaryFormatter();

        // Create a MemoryStream that the object will be serialized into and deserialized from.
        using (Stream stream = new MemoryStream()) 
            // Create a SurrogateSelector.
            SurrogateSelector ss = new SurrogateSelector();

            // Tell the SurrogateSelector that Employee objects are serialized and deserialized 
            // using the EmployeeSerializationSurrogate object.
            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 (SerializationException e) 
                Console.WriteLine("Serialization failed: {0}", e.Message);

            // Rewind the MemoryStream.
            stream.Position = 0;

                // Deserialize the Employee object from the memory stream.
                Employee emp = (Employee) formatter.Deserialize(stream);

                // Verify that it all worked.
                Console.WriteLine("Name = {0}, Address = {1}",, emp.address);
            catch (SerializationException e) 
                Console.WriteLine("Deserialization failed: {0}", e.Message);

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

.NET Framework
Available since 1.1

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

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