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XmlSerializer.UnknownAttribute Event

Occurs when the XmlSerializer encounters an XML attribute of unknown type during deserialization.

Namespace:  System.Xml.Serialization
Assembly:  System.Xml (in System.Xml.dll)

'Declaration
Public Event UnknownAttribute As XmlAttributeEventHandler
'Usage
Dim instance As XmlSerializer 
Dim handler As XmlAttributeEventHandler 

AddHandler instance.UnknownAttribute, handler

By default, after calling the Deserialize method, the XmlSerializer ignores XML attributes of unknown types. However, you can use this event to handle such node types.

If the instance of the class being deserialized contains a field that returns an array of XmlAttribute objects and an XmlAnyAttributeAttribute has been applied to the field, the UnknownAttribute event does not occur. Instead, all unknown XML attributes are collected into the array.

The following example prints information about any unknown attributes encountered while deserializing an XML document.

Imports System
Imports System.IO
Imports System.Xml.Serialization
Imports System.Xml
Imports System.Xml.Schema
Imports Microsoft.VisualBasic

Public Class Group
   Public GroupName As String  
End Class 

Public Class Test
   Shared Sub Main()
      Dim t As Test = new Test()
      ' Deserialize the file containing unknown elements.
      t.DeserializeObject("UnknownAttributes.xml")
   End Sub 

   Private Sub Serializer_UnknownAttribute _
   (sender As Object , e As XmlAttributeEventArgs)
      Console.WriteLine("Unknown Attribute")
      Console.WriteLine(ControlChars.Tab & e.Attr.Name + " " & e.Attr.InnerXml)
      Console.WriteLine(ControlChars.Tab & e.LineNumber & ":"  & e.LineNumber)
      Console.WriteLine(ControlChars.Tab & e.LinePosition & ":"   & e.LinePosition)

      Dim x As Group = CType( e.ObjectBeingDeserialized, Group)
      Console.WriteLine (x.GroupName)
      Console.WriteLine (sender.ToString())
   End Sub 

   Private Sub DeserializeObject(filename As String)
      Dim ser As XmlSerializer = new XmlSerializer(GetType(Group))
      ' Add a delegate to handle unknown element events. 
      AddHandler ser.UnknownAttribute, _
      AddressOf Serializer_UnknownAttribute 
      ' A FileStream is needed to read the XML document. 
     Dim fs As FileStream  = new FileStream(filename, FileMode.Open)
     Dim g  As Group = CType(ser.Deserialize(fs),Group)
     fs.Close()
   End Sub 
End Class
#using <mscorlib.dll>
#using <System.Xml.dll>
#using <System.dll>
using namespace System;
using namespace System::IO;
using namespace System::Xml::Serialization;
using namespace System::Xml;
using namespace System::Xml::Schema;

public __gc class Group{
public:
   String* GroupName;
};

public __gc class Test{
public:
   static void main(){
      Test* t = new Test();
      // Deserialize the file containing unknown elements.
      t->DeserializeObject(S"UnknownAttributes.xml");
   }
private:
   void Serializer_UnknownAttribute(Object* sender, XmlAttributeEventArgs* e){
      Console::WriteLine(S"Unknown Attribute");
      Console::WriteLine(S"\t{0} {1}", e->Attr->Name, e->Attr->InnerXml);
      Console::WriteLine(S"\t LineNumber: {0}", __box(e->LineNumber));
      Console::WriteLine(S"\t LinePosition: {0}", __box(e->LinePosition));

      Group* x  = dynamic_cast<Group*> (e->ObjectBeingDeserialized);
      Console::WriteLine (x->GroupName);
      Console::WriteLine (sender);
   }
private:
   void DeserializeObject(String* filename){
      XmlSerializer* ser = new XmlSerializer(__typeof(Group));
      // Add a delegate to handle unknown element events.
      ser->UnknownAttribute+=new XmlAttributeEventHandler(this, &Test::Serializer_UnknownAttribute);
      // A FileStream is needed to read the XML document.
      FileStream* fs = new FileStream(filename, FileMode::Open);
      Group* g = dynamic_cast<Group*> (ser->Deserialize(fs));
      fs->Close();
   }
};

int main()
{
   Test::main();
}

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, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

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, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0

XNA Framework

Supported in: 3.0, 2.0, 1.0
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