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XmlElementEventHandler Delegate

Represents the method that handles the UnknownElement event of an XmlSerializer.

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

public delegate void XmlElementEventHandler (
	Object sender,
	XmlElementEventArgs e
)
/** @delegate */
public delegate void XmlElementEventHandler (
	Object sender, 
	XmlElementEventArgs e
)
JScript supports the use of delegates, but not the declaration of new ones.

Parameters

sender

The source of the event.

e

A XmlElementEventArgs that contains the event data.

When you create an XmlElementEventHandler delegate, you identify the method that handles the event. To associate the event with your event handler, add an instance of the delegate to the event. The event handler is called whenever the event occurs, unless you remove the delegate. For more information about event handler delegates, see Events and Delegates.

The UnknownElement event occurs only when you call the Deserialize method.

The following example deserializes a class named Group from a file named UnknownElements.xml. Whenever an element is found in the file that has no corresponding member in the class, the UnknownElement event occurs. To try the example, paste the following XML code into a file named UnknownElements.xml.

 <?xml version="1.0" encoding="utf-8"?>
 <Group xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
   <GroupName>MyGroup</GroupName>
   <GroupSize>Large</GroupSize>
   <GroupNumber>444</GroupNumber>
   <GroupBase>West</GroupBase>
 </Group>
using System;
using System.IO;
using System.Xml.Serialization;
using System.Xml;
using System.Xml.Schema;

public class Group{
   public string GroupName;
}

public class Test{
   static void Main(){
      Test t = new Test();
      // Deserialize the file containing unknown elements.
      t.DeserializeObject("UnknownElements.xml");
   }
   private void Serializer_UnknownElement(object sender, XmlElementEventArgs e){
      Console.WriteLine("Unknown Element");
      Console.WriteLine("\t" + e.Element.Name + " " + e.Element.InnerXml);
      Console.WriteLine("\t LineNumber: " + e.LineNumber);
      Console.WriteLine("\t LinePosition: " + e.LinePosition);
      
      Group x  = (Group) e.ObjectBeingDeserialized;
      Console.WriteLine (x.GroupName);
      Console.WriteLine (sender.ToString());
   }
   private void DeserializeObject(string filename){
      XmlSerializer ser = new XmlSerializer(typeof(Group));
      // Add a delegate to handle unknown element events.
      ser.UnknownElement+=new XmlElementEventHandler(Serializer_UnknownElement);
      // A FileStream is needed to read the XML document.
     FileStream fs = new FileStream(filename, FileMode.Open);
     Group g = (Group) ser.Deserialize(fs);
     fs.Close();
   	}
}

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("UnknownElements.xml");
    } //main

    private void Serializer_UnknownElement(Object sender, 
        XmlElementEventArgs e)
    {
        Console.WriteLine("Unknown Element");
        Console.WriteLine("\t" + e.get_Element().get_Name() + " " 
            + e.get_Element().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_UnknownElement

    private void DeserializeObject(String fileName)
    {
        XmlSerializer ser = new XmlSerializer(Group.class.ToType());
        // Add a delegate to handle unknown element events.
        ser.add_UnknownElement(new XmlElementEventHandler(
            Serializer_UnknownElement));
        // 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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