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OnSerializedAttribute Class

When applied to a method, specifies that the method is called after serialization of an object graph.

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

[AttributeUsageAttribute(AttributeTargets.Method, Inherited = false)]
public sealed class OnSerializedAttribute : Attribute

Use the OnSerializedAttribute to manipulate the object after serialization has occurred.

To use the OnSerializedAttribute, the method must contain a StreamingContext parameter. The attribute marks the method to be called by the serialization infrastructure and the StreamingContext provides additional data about the type of serialization taking place. The usage is shown in the following code:

\\ C#
internal void RunThisMethod(StreamingContext context)
    // Code not shown.
' Visual Basic
<OnSerializedAttribute()> _
Private Sub RunThisMethod(context As StreamingContext)
    ' Code not shown.
End Sub

In your code, you can use the word OnSerialized instead of the longer OnSerializedAttribute.

The following example applies the OnDeserializedAttribute, OnSerializingAttribute, OnSerializedAttribute, and OnDeserializingAttribute attributes to methods in a class.

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

public class Test
    public static void Main()
        // Create a new TestSimpleObject object.
        TestSimpleObject obj = new TestSimpleObject();

        Console.WriteLine("\n Before serialization the object contains: ");

        // Open a file and serialize the object into binary format.
        Stream stream = File.Open("DataFile.dat", FileMode.Create);
        BinaryFormatter formatter = new BinaryFormatter();

            formatter.Serialize(stream, obj);

            // Print the object again to see the effect of the  
            Console.WriteLine("\n After serialization the object contains: ");

            // Set the original variable to null.
            obj = null;

            // Open the file "DataFile.dat" and deserialize the object from it.
            stream = File.Open("DataFile.dat", FileMode.Open);

            // Deserialize the object from the data file.
            obj = (TestSimpleObject)formatter.Deserialize(stream);

            Console.WriteLine("\n After deserialization the object contains: ");
        catch (SerializationException se)
            Console.WriteLine("Failed to serialize. Reason: " + se.Message);
        catch (Exception exc)
            Console.WriteLine("An exception occurred. Reason: " + exc.Message);
            obj = null;
            formatter = null;


// This is the object that will be serialized and deserialized.
public class TestSimpleObject
    // This member is serialized and deserialized with no change. 
    public int member1;

    // The value of this field is set and reset during and  
    // after serialization. 
    private string member2;

    // This field is not serialized. The OnDeserializedAttribute  
    // is used to set the member value after serialization.
    public string member3;

    // This field is set to null, but populated after deserialization. 
    private string member4;

    // Constructor for the class. 
    public TestSimpleObject()
        member1 = 11;
        member2 = "Hello World!";
        member3 = "This is a nonserialized value";
        member4 = null;

    public void Print()
        Console.WriteLine("member1 = '{0}'", member1);
        Console.WriteLine("member2 = '{0}'", member2);
        Console.WriteLine("member3 = '{0}'", member3);
        Console.WriteLine("member4 = '{0}'", member4);

    internal void OnSerializingMethod(StreamingContext context)
        member2 = "This value went into the data file during serialization.";

    internal void OnSerializedMethod(StreamingContext context)
        member2 = "This value was reset after serialization.";

    internal void OnDeserializingMethod(StreamingContext context)
        member3 = "This value was set during deserialization";

    internal void OnDeserializedMethod(StreamingContext context)
        member4 = "This value was set after deserialization.";

// Output: 
//  Before serialization the object contains:  
// member1 = '11' 
// member2 = 'Hello World!' 
// member3 = 'This is a nonserialized value' 
// member4 = '' 
//  After serialization the object contains:  
// member1 = '11' 
// member2 = 'This value was reset after serialization.' 
// member3 = 'This is a nonserialized value' 
// member4 = '' 
//  After deserialization the object contains:  
// member1 = '11' 
// member2 = 'This value went into the data file during serialization.' 
// member3 = 'This value was set during deserialization' 
// member4 = 'This value was set after deserialization.'


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

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

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

.NET Framework

Supported in: 3.5, 3.0, 2.0

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