XmlNodeChangedEventHandler Delegate

Definition

Namespace:

System.Xml

Assembly:

System.Xml.ReaderWriter.dll

Represents the method that handles NodeChanged, NodeChanging, NodeInserted, NodeInserting, NodeRemoved and NodeRemoving events.

public delegate void XmlNodeChangedEventHandler(System::Object ^ sender, XmlNodeChangedEventArgs ^ e);

public delegate void XmlNodeChangedEventHandler(object sender, XmlNodeChangedEventArgs e);

type XmlNodeChangedEventHandler = delegate of obj * XmlNodeChangedEventArgs -> unit

Public Delegate Sub XmlNodeChangedEventHandler(sender As Object, e As XmlNodeChangedEventArgs)

Parameters

sender

Object

The source of the event.

e

XmlNodeChangedEventArgs

An XmlNodeChangedEventArgs containing the event data.

Examples

The following example shows how to handle the NodeChanged and NodeInserted events.

#using <System.Xml.dll>

using namespace System;
using namespace System::IO;
using namespace System::Xml;
public ref class Sample
{
public:
   void Run( String^ args )
   {
      // Create and load the XML document.
      Console::WriteLine( "Loading file {0} ...", args );
      XmlDocument^ doc = gcnew XmlDocument;
      doc->Load( args );
      
      //Create the event handlers.
      doc->NodeChanged += gcnew XmlNodeChangedEventHandler( this, &Sample::MyNodeChangedEvent );
      doc->NodeInserted += gcnew XmlNodeChangedEventHandler( this, &Sample::MyNodeInsertedEvent );
      
      // Change the book price.
      doc->DocumentElement->LastChild->InnerText = "5.95";
      
      // Add a new element.
      XmlElement^ newElem = doc->CreateElement( "style" );
      newElem->InnerText = "hardcover";
      doc->DocumentElement->AppendChild( newElem );
      Console::WriteLine( "\r\nDisplay the modified XML..." );
      Console::WriteLine( doc->OuterXml );
   }

   // Handle the NodeChanged event.
private:
   void MyNodeChangedEvent( Object^ /*src*/, XmlNodeChangedEventArgs^ args )
   {
      Console::Write( "Node Changed Event: <{0}> changed", args->Node->Name );
      if ( args->Node->Value != nullptr )
      {
         Console::WriteLine( " with value  {0}", args->Node->Value );
      }
      else
            Console::WriteLine( "" );
   }

   // Handle the NodeInserted event.
   void MyNodeInsertedEvent( Object^ /*src*/, XmlNodeChangedEventArgs^ args )
   {
      Console::Write( "Node Inserted Event: <{0}> inserted", args->Node->Name );
      if ( args->Node->Value != nullptr )
      {
         Console::WriteLine( " with value {0}", args->Node->Value );
      }
      else
            Console::WriteLine( "" );
   }
};
// End class 

int main()
{
   Sample^ mySample = gcnew Sample;
   mySample->Run( "book.xml" );
}

using System;
using System.IO;
using System.Xml;

namespace Microsoft.Samples.Xml
{
    public class Sample
    {
        private const String filename = "book.xml";

        public static void Main()
        {
            Sample mySample = new Sample();
            mySample.Run(filename);
        }

        public void Run(String args)
        {

            // Create and load the XML document.
            Console.WriteLine("Loading file {0} ...", args);
            XmlDocument doc = new XmlDocument();
            doc.Load(args);

            //Create the event handlers.
            doc.NodeChanged += new XmlNodeChangedEventHandler(this.MyNodeChangedEvent);
            doc.NodeInserted += new XmlNodeChangedEventHandler(this.MyNodeInsertedEvent);

            // Change the book price.
            doc.DocumentElement.LastChild.InnerText = "5.95";

            // Add a new element.
            XmlElement newElem = doc.CreateElement("style");
            newElem.InnerText = "hardcover";
            doc.DocumentElement.AppendChild(newElem);

            Console.WriteLine("\r\nDisplay the modified XML...");
            Console.WriteLine(doc.OuterXml);
        }

        // Handle the NodeChanged event.
        private void MyNodeChangedEvent(Object source, XmlNodeChangedEventArgs args)
        {
            Console.Write("Node Changed Event: <{0}> changed", args.Node.Name);
            if (args.Node.Value != null)
            {
                Console.WriteLine(" with value  {0}", args.Node.Value);
            }
            else
            {
                Console.WriteLine("");
            }
        }

        // Handle the NodeInserted event.
        private void MyNodeInsertedEvent(Object source, XmlNodeChangedEventArgs args)
        {
            Console.Write("Node Inserted Event: <{0}> inserted", args.Node.Name);
            if (args.Node.Value != null)
            {
                Console.WriteLine(" with value {0}", args.Node.Value);
            }
            else
            {
                Console.WriteLine("");
            }
        }
    } // End class

Imports System.IO
Imports System.Xml

Namespace Microsoft.Samples.Xml

    Public Class Sample

        Private Const filename As String = "book.xml"

        Public Shared Sub Main()

            Dim mySample As Sample = New Sample()
            mySample.Run(filename)
        End Sub

        Public Sub Run(ByVal args As String)

            ' Create and load the XML document.
            Console.WriteLine("Loading file {0} ...", args)
            Dim doc As XmlDocument = New XmlDocument()
            doc.Load(args)

            'Create the event handlers.
            AddHandler doc.NodeChanged, AddressOf MyNodeChangedEvent
            AddHandler doc.NodeInserted, AddressOf MyNodeInsertedEvent

            ' Change the book price.
            doc.DocumentElement.LastChild.InnerText = "5.95"

            ' Add a new element.
            Dim newElem As XmlElement = doc.CreateElement("style")
            newElem.InnerText = "hardcover"
            doc.DocumentElement.AppendChild(newElem)

            Console.WriteLine()
            Console.WriteLine("Display the modified XML...")
            Console.WriteLine(doc.OuterXml)

        End Sub

        ' Handle the NodeChanged event.
        Private Sub MyNodeChangedEvent(ByVal source As Object, ByVal args As XmlNodeChangedEventArgs)
            Console.Write("Node Changed Event: <{0}> changed", args.Node.Name)
            If Not (args.Node.Value Is Nothing) Then
                Console.WriteLine(" with value  {0}", args.Node.Value)
            Else
                Console.WriteLine("")
            End If
        End Sub

        ' Handle the NodeInserted event.
        Private Sub MyNodeInsertedEvent(ByVal source As Object, ByVal args As XmlNodeChangedEventArgs)
            Console.Write("Node Inserted Event: <{0}> inserted", args.Node.Name)
            If Not (args.Node.Value Is Nothing) Then
                Console.WriteLine(" with value {0}", args.Node.Value)
            Else
                Console.WriteLine("")
            End If
        End Sub

    End Class

End Namespace

The example uses the file book.xml as input.

<!--sample XML fragment-->
<book genre='novel' ISBN='1-861003-78' misc='sale-item'>
  <title>The Handmaid's Tale</title>
  <price>14.95</price>
</book>

Remarks

When you create an XmlNodeChangedEventHandler 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 Handling and Raising Events.

Extension Methods

GetMethodInfo(Delegate)

Gets an object that represents the method represented by the specified delegate.