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XmlSerializer.UnknownElement Event

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

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

public event XmlElementEventHandler UnknownElement

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.

NoteNote:

If the XmlAnyElementAttribute is applied to a field that returns an array of XmlElement objects, all unknown elements are collected in the array. In that case, the UnknownElement event does not occur.

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();
   	}
}
#using <mscorlib.dll>
#using <System.Xml.dll>
using namespace System;
using namespace System::IO;
using namespace System::Xml::Serialization;
using namespace System::Xml;
using namespace System::Xml::Schema;

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

__gc public class Test
{
public:
   void Serializer_UnknownElement(Object* sender, XmlElementEventArgs * e) 
   {
      Console::WriteLine(S"Unknown Element");
      Console::Write(S"\t {0}", e -> Element -> Name);
      Console::WriteLine(S" {0}", e -> Element -> 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);
   }
   void DeserializeObject(String* filename)
   {
      XmlSerializer* ser = new XmlSerializer(__typeof(Group));
      // Add a delegate to handle unknown element events.
      ser -> UnknownElement += new XmlElementEventHandler(this, &Test::Serializer_UnknownElement);
      // 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* t = new Test();
   // Deserialize the file containing unknown elements.
   t -> DeserializeObject(S"UnknownElements.xml");
}

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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