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XmlAttributeEventHandler Delegate

Represents the method that handles the UnknownAttribute

Namespace:  System.Xml.Serialization
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)

Parameters

sender
Type: System.Object

The source of the event.

e
Type: System.Xml.Serialization.XmlAttributeEventArgs

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
#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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