XmlValidatingReader.ResolveEntity Method ()

 

Resolves the entity reference for EntityReference nodes.

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

public override void ResolveEntity()

Exception Condition
InvalidOperationException

The reader is not positioned on an EntityReference node.

System_CAPS_noteNote

The XmlValidatingReader class is obsolete in .NET Framework 2.0. You can create a validating XmlReader instance by using the XmlReaderSettings class and the Create method. For more information, see the Remarks section of the XmlReader reference page.

If the reader is positioned on an EntityReference node (XmlNodeType.EntityReference), if Read is called after calling this method, the entity replacement text is parsed. After the entity replacement text is finished, an EndEntity node is returned to close the entity reference scope.

System_CAPS_noteNote

After calling this method, if the entity is part of an attribute value, you must call ReadAttributeValue to step into the entity.

The following example uses ResolveEntity to expand a general entity.

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

public class Sample
{
  public static void Main()
  {
     XmlValidatingReader reader = null;
     XmlTextReader txtreader = null;

     try
     {
       //Create and load the XmlTextReader with the XML file. 
       txtreader = new XmlTextReader("book1.xml");
       txtreader.WhitespaceHandling = WhitespaceHandling.None;

       //Create the XmlValidatingReader over the XmlTextReader.
       //Set the reader to not expand general entities.
       reader = new XmlValidatingReader(txtreader);
       reader.ValidationType = ValidationType.None;
       reader.EntityHandling = EntityHandling.ExpandCharEntities;

       reader.MoveToContent();  //Move to the root element.
       reader.Read();  //Move to title start tag.
       reader.Skip();  //Skip the title element.

       //Read the misc start tag.  The reader is now positioned on
       //the entity reference node.
       reader.ReadStartElement(); 

       //Because EntityHandling is set to ExpandCharEntities, you must call 
       //ResolveEntity to expand the entity.  The entity replacement text is 
       //then parsed and returned as a child node.         
       Console.WriteLine("Expand the entity...");
       reader.ResolveEntity();  

       Console.WriteLine("The entity replacement text is returned as a text node.");
       reader.Read();  
       Console.WriteLine("NodeType: {0} Value: {1}", reader.NodeType ,reader.Value);

       Console.WriteLine("An EndEntity node closes the entity reference scope.");
       reader.Read();
       Console.WriteLine("NodeType: {0} Name: {1}", reader.NodeType,reader.Name);

    }
    finally
    {
       if (reader != null)
         reader.Close();
    }
  }
}

The example uses the file, book1.xml, as input.


<?xml version='1.0' ?>
<!DOCTYPE book [<!ENTITY h 'hardcover'>]>
<book>
  <title>Pride And Prejudice</title>
  <misc>&h;</misc>
</book>

.NET Framework
Available since 1.1
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