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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

/** @event */
public void add_UnknownAttribute (XmlAttributeEventHandler value)

/** @event */
public void remove_UnknownAttribute (XmlAttributeEventHandler value)

JScript supports the use of events, but not the declaration of new ones.

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

import System.*;
import System.IO.*;
import System.Xml.Serialization.*;
import System.Xml.*;
import System.Xml.Schema.*;

public class Group
{
    public String groupName;
} //Group

public class Test
{
    public static void main(String[] args)
    {
        Test t = new Test();
        // Deserialize the file containing unknown elements.
        t.DeserializeObject("UnknownAttributes.xml");
    } //main

    private void Serializer_UnknownAttribute(Object sender,
        XmlAttributeEventArgs e)
    {
        Console.WriteLine("Unknown Attribute");
        Console.WriteLine("\t" + e.get_Attr().get_Name() + " "
            + e.get_Attr().get_InnerXml());
        Console.WriteLine("\t LineNumber: " + e.get_LineNumber());
        Console.WriteLine("\t LinePosition: " + e.get_LinePosition());

        Group x = (Group)e.get_ObjectBeingDeserialized();
        Console.WriteLine(x.groupName);
        Console.WriteLine(sender.ToString());
    } //Serializer_UnknownAttribute

    private void DeserializeObject(String filename)
    {
        XmlSerializer ser = new XmlSerializer(Group.class.ToType());

        // Add a delegate to handle unknown element events.
        ser.add_UnknownAttribute(new XmlAttributeEventHandler
            (Serializer_UnknownAttribute));

        // A FileStream is needed to read the XML document.
        FileStream fs = new FileStream(filename, FileMode.Open);
        Group g = (Group)ser.Deserialize(fs);
        fs.Close();
    } //DeserializeObject
} //Test

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0
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