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ObjectStateFormatter Class

Serializes and deserializes object graphs that represent the state of an object. This class cannot be inherited.

Namespace:  System.Web.UI
Assembly:  System.Web (in System.Web.dll)

[AspNetHostingPermissionAttribute(SecurityAction.LinkDemand, Level = AspNetHostingPermissionLevel.Minimal)]
public sealed class ObjectStateFormatter : IStateFormatter, 

The ObjectStateFormatter class serializes and deserializes object state graphs in a compact format.

ObjectStateFormatter is used by the PageStatePersister class and classes that derive from it to serialize view state and control state. It is also used by the LosFormatter class to provide object state graph formatting for various parts of the ASP.NET infrastructure.

The ObjectStateFormatter class is optimized to serialize and format many common .NET Framework reference types, as well as constants. The following table lists the types that are optimized.

Additionally, while conventional string types and string arrays are written to and from a serialized binary writer unaltered, some strings are optimized by creating internal string tables. Strings are optimized using these tables if the string has an associated TypeConverter object or if the string is actually an instance of the IndexedString class.

Other types not listed above are binary-serialized using a BinaryFormatter object if they implement the ISerializable interface or are decorated with the SerializableAttribute attribute. The ObjectStateFormatter class is not optimized for any of these serializable types.

If the ObjectStateFormatter class encounters a type that is not serializable, an ArgumentException exception is thrown.

The following code example demonstrates how a class that derives from the PageStatePersister class accesses the StateFormatter property to retrieve an ObjectStateFormatter instance to serialize view state and control state to a stream. This code example is part of a larger example provided for the PageStatePersister class.

// Persist any ViewState and ControlState. 
public override void Save()

    if (ViewState != null || ControlState != null)
        if (Page.Session != null)
            Stream stateStream = GetSecureStream();

            StreamWriter writer = new StreamWriter(stateStream);

            IStateFormatter formatter = this.StateFormatter;
            Pair statePair = new Pair(ViewState, ControlState);

            // Serialize the statePair object to a string.
            string serializedState = formatter.Serialize(statePair);

            throw new InvalidOperationException("Session needed for StreamPageStatePersister.");


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