KnownTypeAttribute Class
Specifies types that should be recognized by the DataContractSerializer when serializing or deserializing a given type.
Assembly: System.Runtime.Serialization (in System.Runtime.Serialization.dll)
The KnownTypeAttribute type exposes the following members.
| Name | Description | |
|---|---|---|
![]() ![]() | KnownTypeAttribute(String) | Initializes a new instance of the KnownTypeAttribute class with the name of a method that returns an IEnumerable of known types. |
![]() ![]() | KnownTypeAttribute(Type) | Initializes a new instance of the KnownTypeAttribute class with the specified type. |
| Name | Description | |
|---|---|---|
![]() ![]() | MethodName | Gets the name of a method that will return a list of types that should be recognized during serialization or deserialization. |
![]() ![]() | Type | Gets the type that should be recognized during serialization or deserialization by the DataContractSerializer. |
![]() | TypeId | When implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute.) |
| Name | Description | |
|---|---|---|
![]() ![]() | Equals | Infrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.) |
![]() ![]() | Finalize | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.) |
![]() ![]() | GetHashCode | Returns the hash code for this instance. (Inherited from Attribute.) |
![]() ![]() | GetType | Gets the Type of the current instance. (Inherited from Object.) |
![]() | 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.) |
![]() | Match | When overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.) |
![]() ![]() | MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
![]() ![]() | ToString | Returns a string that represents the current object. (Inherited from Object.) |
| Name | Description | |
|---|---|---|
![]() ![]() | _Attribute.GetIDsOfNames | Maps a set of names to a corresponding set of dispatch identifiers. (Inherited from Attribute.) |
![]() ![]() | _Attribute.GetTypeInfo | Retrieves the type information for an object, which can be used to get the type information for an interface. (Inherited from Attribute.) |
![]() ![]() | _Attribute.GetTypeInfoCount | Retrieves the number of type information interfaces that an object provides (either 0 or 1). (Inherited from Attribute.) |
![]() ![]() | _Attribute.Invoke | Provides access to properties and methods exposed by an object. (Inherited from Attribute.) |
Apply the KnownTypeAttribute attribute to a type to indicate to the DataContractSerializer types that should be recognized when serializing or deserializing an instance of the type to which the attribute is applied. This attribute could also be recognized by other serializers that understand data contracts.
Note |
|---|
In your code, you can use the word KnownType instead of the longer KnownTypeAttribute. |
You can either apply exactly one KnownTypeAttribute instance with the MethodName property set, or one or more KnownTypeAttribute instances with the Type property set.
The following example shows a type named Person and a type named IDInformation that should be recognized when serializing or deserializing the Person type.
Imports System Imports System.Collections.Generic Imports System.Collections Imports System.Text Imports System.IO Imports System.Runtime.Serialization Imports System.Xml Class Program Shared Sub Main(ByVal args() As String) Try Serialize("KnownTypeAttributeExample.xml") Deserialize("KnownTypeAttributeExample.xml") ' Run this twice. The second time, comment out the ' Serialize call and comment out the ' KnownTypeAttribute on the Person class. The ' deserialization will then fail. Catch exc As SerializationException Console.WriteLine("{0}: {1}", exc.Message, exc.StackTrace) Finally Console.WriteLine("Press Enter to exit...") Console.ReadLine() End Try End Sub Public Shared Sub Serialize(ByVal path As String) Dim p As New Person() p.Miscellaneous.Add(DateTime.Now, "Hello") p.Miscellaneous.Add(DateTime.Now.AddSeconds(1), "World") Dim w As New IDInformation() w.ID = "1111 00000" p.Miscellaneous.Add(DateTime.Now.AddSeconds(2), w) Dim ser As New DataContractserializer(GetType(Person)) Using fs As New FileStream(path, FileMode.OpenOrCreate) ser.WriteObject(fs, p) End Using End Sub Public Shared Sub Deserialize(ByVal path As String) Dim ser As New DataContractserializer(GetType(Person)) Using fs As New FileStream(path, FileMode.OpenOrCreate) Dim p2 As Person = ser.ReadObject(fs) Console.WriteLine("Count {0}", p2.Miscellaneous.Count) For Each de As DictionaryEntry In p2.Miscellaneous Console.WriteLine("Key {0} Value: {1}", de.Key, _ de.Value) If TypeOf (de.Value) Is IDInformation Then Dim www As IDInformation = de.Value Console.WriteLine( _ "Found ID Information. ID: {0}", www.ID) End If Next End Using End Sub ' Apply the KnownTypeAttribute to the class that ' includes a member that returns a Hashtable. <System.Runtime.Serialization.KnownType(GetType(IDInformation))> _ <DataContract()> _ Public Class Person Implements IExtensibleDataObject Private MiscellaneousValue As New Hashtable() Private ExtensionDataObjectValue As ExtensionDataObject Public Property ExtensionData() As ExtensionDataObject _ Implements IExtensibleDataObject.ExtensionData Get Return ExtensionDataObjectValue End Get Set(ByVal value As ExtensionDataObject) ExtensionDataObjectValue = value End Set End Property <DataMember()> _ Public Property Miscellaneous() As Hashtable Get Return MiscellaneousValue End Get Set(ByVal value As Hashtable) MiscellaneousValue = value End Set End Property End Class <DataContract()> _ Public Class IDInformation Implements IExtensibleDataObject Private ExtensionDataObjectValue As ExtensionDataObject Public Property ExtensionData() As ExtensionDataObject _ Implements IExtensibleDataObject.ExtensionData Get Return ExtensionDataObjectValue End Get Set(ByVal value As ExtensionDataObject) ExtensionDataObjectValue = value End Set End Property <DataMember()> _ Public ID As String End Class End Class
Windows 7, Windows Vista SP1 or later, Windows XP SP3, 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.






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