XmlValidatingReader.EntityHandling Property

 
System_CAPS_noteNote

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Gets or sets a value that specifies how the reader handles entities.

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

Public Property EntityHandling As EntityHandling

Property Value

Type: System.Xml.EntityHandling

One of the EntityHandling values. If no EntityHandling is specified, it defaults to EntityHandling.ExpandEntities.

Exception Condition
ArgumentOutOfRangeException

Invalid value was specified.

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The XmlValidatingReader class is obsolete in .NET Framework 2.0.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.

This property can be changed and takes effect after the next Read call.

When EntityHandling is set to ExpandCharEntities, attribute values are only partially normalized. The reader normalizes each individual text node independently from the content of adjacent entity reference nodes.

To illustrate the difference between the entity handling modes consider the following XML:

<!DOCTYPE doc [<!ENTITY num "123">]>
 <doc> &#65; &num; </doc>

When EntityHandling is set to ExpandEntities the "doc" element node contains one text node with the expanded entity text:

Depth

NodeType

Name

Value

1

Text

A 123

When EntityHandling is set to ExpandCharEntites, and WhitespaceHandling is set to Significant or All, the "doc" element expands the character entity and returns the general entity as a node:

Depth

NodeType

Name

Value

1

Text

A

1

EntityReference

num

1

SignificantWhitespace

The following example uses the ResolveEntity method to expand a general entity.

Option Strict
Option Explicit

Imports System
Imports System.IO
Imports System.Xml

Public Class Sample

   Public Shared Sub Main()
      Dim reader As XmlValidatingReader = Nothing
      Dim txtreader As XmlTextReader = Nothing

      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 Not (reader Is Nothing) Then
            reader.Close()
         End If
      End Try
   End Sub 'Main
End Class 'Sample 

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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