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XmlAttributeAttribute Class

Specifies that the XmlSerializer must serialize the class member as an XML attribute.

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

public class XmlAttributeAttribute : Attribute

The XmlAttributeAttribute belongs to a family of attributes that controls how the XmlSerializer serializes, or deserializes, an object. For a complete list of similar attributes, see Attributes That Control XML Serialization.

When applied to a public field or property, the XmlAttributeAttribute informs the XmlSerializer to serialize the member as an XML attribute. By default, the XmlSerializer serializes public fields and properties as XML elements.

You can assign the XmlAttributeAttribute only to public fields or public properties that return a value (or array of values) that can be mapped to one of the XML Schema definition language (XSD) simple types (including all built-in datatypes derived from the XSD anySimpleType type). The possible types include any that can be mapped to the XSD simple types, including Guid, Char, and enumerations. See the DataType property for a list of XSD types and how they are mapped to.NET data types.

There are two special attributes that can be set with the XmlAttributeAttribute : the xml:lang (specifies language) and xml:space (specifies how to handle white space) attributes. These attributes are intended to convey information that is relevant only to an application processing the XML. Examples of setting these are shown in the following code.

 public string Lang;
 // Set this to 'default' or 'preserve'.
 Namespace = "")]
 public string Space 
 [Visual Basic]
 <XmlAttribute("xml:lang")> _
 Public Lang As String 
 ' Set this to 'default' or 'preserve'.
 <XmlAttribute("space", _
 Namespace:= "")> _
 Public Space As String

For more information about using attributes, see Extending Metadata Using Attributes.


You can use the word XmlAttribute in your code instead of the longer XmlAttributeAttribute.

The following example serializes a class that contains several fields to which the XmlAttributeAttribute is applied.

using System;
using System.IO;
using System.Xml;
using System.Xml.Serialization;
using System.Xml.Schema;

public class Group
   [XmlAttribute (Namespace = "")]
   public string GroupName;

   [XmlAttribute(DataType = "base64Binary")]
   public Byte [] GroupNumber;

   [XmlAttribute(DataType = "date", AttributeName = "CreationDate")]
   public DateTime Today;

public class Run
   public static void Main()
      Run test = new Run();

   public void SerializeObject(string filename)
      // Create an instance of the XmlSerializer class.
      XmlSerializer mySerializer =  
      new XmlSerializer(typeof(Group));

      // Writing the file requires a TextWriter.
      TextWriter writer = new StreamWriter(filename);

      // Create an instance of the class that will be serialized.
      Group myGroup = new Group();

      // Set the object properties.
      myGroup.GroupName = ".NET";

      Byte [] hexByte = new Byte[2]{Convert.ToByte(100),
      myGroup.GroupNumber = hexByte;

      DateTime myDate = new DateTime(2001,1,10);
      myGroup.Today = myDate;

      // Serialize the class, and close the TextWriter.
      mySerializer.Serialize(writer, myGroup);
#using <mscorlib.dll>
#using <System.Xml.dll>
using namespace System;
using namespace System::IO;
using namespace System::Xml;
using namespace System::Xml::Serialization;
using namespace System::Xml::Schema;

public __gc class Group
   [XmlAttributeAttribute (Namespace = S"")]
   String* GroupName;

   [XmlAttributeAttribute(DataType = S"base64Binary")]
   Byte GroupNumber[];

   [XmlAttributeAttribute(DataType = S"date", AttributeName = S"CreationDate")]
   DateTime Today;

void SerializeObject(String* filename)
   // Create an instance of the XmlSerializer class.
   XmlSerializer* mySerializer =  
      new XmlSerializer(__typeof(Group));

   // Writing the file requires a TextWriter.
   TextWriter* writer = new StreamWriter(filename);

   // Create an instance of the class that will be serialized.
   Group* myGroup = new Group();

   // Set the object properties.
   myGroup->GroupName = S".NET";

   Byte hexByte[] = {Convert::ToByte(100),
   myGroup->GroupNumber = hexByte;

   DateTime myDate = DateTime(2001,1,10);
   myGroup->Today = myDate;

   // Serialize the class, and close the TextWriter.
   mySerializer->Serialize(writer, myGroup);

int main()


Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0
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