XmlTextReader.ReadAttributeValue Method

Definition

Namespace:

System.Xml

Assembly:

System.Xml.ReaderWriter.dll

Source:

XmlTextReader.cs

Parses the attribute value into one or more Text, EntityReference, or EndEntity nodes.

public:
 override bool ReadAttributeValue();

public override bool ReadAttributeValue ();

override this.ReadAttributeValue : unit -> bool

Public Overrides Function ReadAttributeValue () As Boolean

Returns

Boolean

true if there are nodes to return.

false if the reader is not positioned on an attribute node when the initial call is made or if all the attribute values have been read.

An empty attribute, such as, misc="", returns true with a single node with a value of String.Empty.

Examples

The following example reads an attribute with text and entity nodes.

#using <System.Xml.dll>

using namespace System;
using namespace System::IO;
using namespace System::Xml;
int main()
{
   XmlTextReader^ reader = nullptr;
   __try
   {
      
      // Create the XML fragment to be parsed.
      String^ xmlFrag = "<book genre='novel' misc='sale-item &h; 1987'></book>";
      
      // Create the XmlParserContext.
      XmlParserContext^ context;
      String^ subset = "<!ENTITY h 'hardcover'>";
      context = gcnew XmlParserContext( nullptr,nullptr,"book",nullptr,nullptr,subset,"","",XmlSpace::None );
      
      // Create the reader.
      reader = gcnew XmlTextReader( xmlFrag,XmlNodeType::Element,context );
      
      // Read the misc attribute. The attribute is parsed
      // into multiple text and entity reference nodes.
      reader->MoveToContent();
      reader->MoveToAttribute( "misc" );
      while ( reader->ReadAttributeValue() )
      {
         if ( reader->NodeType == XmlNodeType::EntityReference )
                  Console::WriteLine( " {0} {1}", reader->NodeType, reader->Name );
         else
                  Console::WriteLine( " {0} {1}", reader->NodeType, reader->Value );
      }
   }
   __finally
   {
      if ( reader != nullptr )
            reader->Close();
   }

}

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

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

    try
    {
       //Create the XML fragment to be parsed.
       string xmlFrag ="<book genre='novel' misc='sale-item &h; 1987'></book>";

       //Create the XmlParserContext.
       XmlParserContext context;
       string subset = "<!ENTITY h 'hardcover'>";
       context = new XmlParserContext(null, null, "book", null, null, subset, "", "", XmlSpace.None);

       //Create the reader.
       reader = new XmlTextReader(xmlFrag, XmlNodeType.Element, context);

       //Read the misc attribute. The attribute is parsed
       //into multiple text and entity reference nodes.
       reader.MoveToContent();
       reader.MoveToAttribute("misc");
       while (reader.ReadAttributeValue()){
          if (reader.NodeType==XmlNodeType.EntityReference)
            Console.WriteLine("{0} {1}", reader.NodeType, reader.Name);
          else
             Console.WriteLine("{0} {1}", reader.NodeType, reader.Value);
        }
     }
     finally
     {
        if (reader != null)
          reader.Close();
      }
  }
} // End class

Imports System.IO
Imports System.Xml

Public Class Sample

    Public Shared Sub Main()

        Dim reader As XmlTextReader = Nothing

        Try
            ' Create the XML fragment to be parsed.
            Dim xmlFrag As String = "<book genre='novel' misc='sale-item &h; 1987'></book>"
 
            Dim subset As String = "<!ENTITY h 'hardcover'>"
            ' Create the XmlParserContext.
            Dim context As New XmlParserContext(Nothing, Nothing, "book", Nothing, Nothing, subset, "", "", XmlSpace.None)
        
            'Create the reader.
            reader = New XmlTextReader(xmlFrag, XmlNodeType.Element, context)
  
            'Read the misc attribute. The attribute is parsed
            'into multiple text and entity reference nodes.
            reader.MoveToContent()
            reader.MoveToAttribute("misc")
            While (reader.ReadAttributeValue())
                If (reader.NodeType = XmlNodeType.EntityReference)
                    Console.WriteLine($"{reader.NodeType} {reader.Name}")
                Else
                    Console.WriteLine($"{reader.NodeType} {reader.Value}")
                End If
            End While

        Finally 
            If reader IsNot Nothing
                reader.Close()
            End if
        End Try
    End Sub
End Class

Remarks

Note

Starting with the .NET Framework 2.0, we recommend that you create XmlReader instances by using the XmlReader.Create method to take advantage of new functionality.

Use this method after calling MoveToAttribute to read through the text or entity reference nodes that make up the attribute value. The Depth of the attribute value nodes is one plus the depth of the attribute node; it increments and decrements by one when you step into and out of general entity references.

See also

• XmlReader