XmlAttributeEventHandler Delegate
Assembly: System.Xml (in system.xml.dll)
'Declaration Public Delegate Sub XmlAttributeEventHandler ( _ sender As Object, _ e As XmlAttributeEventArgs _ ) 'Usage Dim instance As New XmlAttributeEventHandler(AddressOf HandlerMethod)
/** @delegate */ public delegate void XmlAttributeEventHandler ( Object sender, XmlAttributeEventArgs e )
Not applicable.
Parameters
- sender
The source of the event.
- e
An XmlAttributeEventArgs that contains the event data.
When you create an XmlAttributeEventHandler 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 UnknownAttribute event occurs only when an object is being deserialized with the Deserialize method.
The following example deserializes a class named Group from a file named UnknownAttributes.xml. Whenever an element is found in the file that has no corresponding member in the class, the UnknownAttribute event occurs. To try the example, paste the following XML code into a file named UnknownAttributes.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" GroupType = 'Technical' GroupNumber = '42' GroupBase = 'Red'> <GroupName>MyGroup</GroupName> </Group>
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 Server 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 Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.Reference
System.Xml.Serialization NamespaceXmlNodeEventHandler
Deserialize
XmlSerializer
XmlAttributes
Other Resources
Introducing XML SerializationHow to: Specify an Alternate Element Name for an XML Stream
Controlling XML Serialization Using Attributes
Examples of XML Serialization
XML Schema Definition Tool (Xsd.exe)