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OptionalFieldAttribute Class

.NET Framework 4

Specifies that a field can be missing from a serialization stream so that the BinaryFormatter and the SoapFormatter does not throw an exception.

System.Object
  System.Attribute
    System.Runtime.Serialization.OptionalFieldAttribute

Namespace:  System.Runtime.Serialization
Assembly:  mscorlib (in mscorlib.dll)
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[ComVisibleAttribute(true)]
[AttributeUsageAttribute(AttributeTargets.Field, Inherited = false)]
public sealed class OptionalFieldAttribute : Attribute

The OptionalFieldAttribute type exposes the following members.

  Name Description
Public method OptionalFieldAttribute Initializes a new instance of the OptionalFieldAttribute class.
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  Name Description
Public property TypeId When implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute.)
Public property VersionAdded This property is unused and is reserved.
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  Name Description
Public method Equals Infrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.)
Protected method Finalize Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public method GetHashCode Returns the hash code for this instance. (Inherited from Attribute.)
Public method GetType Gets the Type of the current instance. (Inherited from Object.)
Public method IsDefaultAttribute When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class. (Inherited from Attribute.)
Public method Match When overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)
Protected method MemberwiseClone Creates a shallow copy of the current Object. (Inherited from Object.)
Public method ToString Returns a string that represents the current object. (Inherited from Object.)
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  Name Description
Explicit interface implemetation Private method _Attribute.GetIDsOfNames Maps a set of names to a corresponding set of dispatch identifiers. (Inherited from Attribute.)
Explicit interface implemetation Private method _Attribute.GetTypeInfo Retrieves the type information for an object, which can be used to get the type information for an interface. (Inherited from Attribute.)
Explicit interface implemetation Private method _Attribute.GetTypeInfoCount Retrieves the number of type information interfaces that an object provides (either 0 or 1). (Inherited from Attribute.)
Explicit interface implemetation Private method _Attribute.Invoke Provides access to properties and methods exposed by an object. (Inherited from Attribute.)
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This attribute allows you to specify that new fields in a serializable type (a type to which the SerializableAttribute is applied to) are ignored by the BinaryFormatter or the SoapFormatter. This enables version-tolerant serialization of types created for older versions of an application that serializes data. For example, when the formatters encounter a stream produced by a version that does not include the new fields, no exception is thrown, and the existing data on the older type is processed as normal.

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.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.
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Is this true?
I never  had any problem not using OptionalField attribute.
Once again, i did exactly what should have caused exception:
- Created sample class, marked as Serializable
- Persisted it into a file using BinaryFormatter
- Now, i included two extra fields (deleted one existing field)
- Tried deserializing the stream (serailized in step 2). It happened successfully, no Excpetion what so ever.
I have used both 2.0, 3.5 .NET versions.
Can anyone please look into this?
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