XmlWriter.WriteAttributeString Method

Definition

Namespace:

System.Xml

Assemblies:

netstandard.dll, System.Xml.ReaderWriter.dll

When overridden in a derived class, writes an attribute with the specified value.

Overloads

WriteAttributeString(String, String, String, String)	When overridden in a derived class, writes out the attribute with the specified prefix, local name, namespace URI, and value.
WriteAttributeString(String, String, String)	When overridden in a derived class, writes an attribute with the specified local name, namespace URI, and value.
WriteAttributeString(String, String)	When overridden in a derived class, writes out the attribute with the specified local name and value.

Remarks

For the asynchronous version of this method, see WriteElementStringAsync.

WriteAttributeString(String, String, String, String)

Source:

XmlWriter.cs

When overridden in a derived class, writes out the attribute with the specified prefix, local name, namespace URI, and value.

C#

public void WriteAttributeString(string? prefix, string localName, string? ns, string? value);

Parameters

prefix

String

The namespace prefix of the attribute.

localName

String

The local name of the attribute.

ns

String

The namespace URI of the attribute.

value

String

The value of the attribute.

Exceptions

InvalidOperationException

The state of writer is not WriteState.Element or writer is closed.

-or-

An XmlWriter method was called before a previous asynchronous operation finished. In this case, InvalidOperationException is thrown with the message "An asynchronous operation is already in progress."

ArgumentException

The xml:space or xml:lang attribute value is invalid.

XmlException

The localName or ns is null.

Examples

The following example uses the WriteAttributeString method to write a namespace declaration.

C#

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

public class Sample {

  public static void Main() {

     XmlWriter writer = null;

     writer = XmlWriter.Create("sampledata.xml");

     // Write the root element.
     writer.WriteStartElement("book");

     // Write the xmlns:bk="urn:book" namespace declaration.
     writer.WriteAttributeString("xmlns","bk", null,"urn:book");

     // Write the bk:ISBN="1-800-925" attribute.
     writer.WriteAttributeString("ISBN", "urn:book", "1-800-925");

     writer.WriteElementString("price", "19.95");

     // Write the close tag for the root element.
     writer.WriteEndElement();

     // Write the XML to file and close the writer.
     writer.Flush();
     writer.Close();
  }
}

Remarks

This method writes out the attribute with a user defined namespace prefix and associates it with the given namespace. If the prefix is "xmlns" then this method also treats this as a namespace declaration and associates the declared prefix with the namespace URI provided in the given attribute value. In this case the ns argument can be null.

WriteAttributeString does the following:

• If the attribute value includes double or single quotes, they are replaced with " and ' respectively.

• If writing an xml:space attribute, the writer verifies the attribute value is valid. (Valid values are preserve or default.)

• If writing an xml:lang attribute, the writer does not verify that the attribute value is valid according to the W3C XML 1.0 recommendation.

For the asynchronous version of this method, see WriteAttributeStringAsync.

WriteAttributeString(String, String, String)

Source:

XmlWriter.cs

When overridden in a derived class, writes an attribute with the specified local name, namespace URI, and value.

C#

public void WriteAttributeString(string localName, string? ns, string? value);

Parameters

localName

String

The local name of the attribute.

ns

String

The namespace URI to associate with the attribute.

value

String

The value of the attribute.

Exceptions

InvalidOperationException

The state of writer is not WriteState.Element or writer is closed.

-or-

An XmlWriter method was called before a previous asynchronous operation finished. In this case, InvalidOperationException is thrown with the message "An asynchronous operation is already in progress."

ArgumentException

The xml:space or xml:lang attribute value is invalid.

Examples

The following example uses the WriteAttributeString method to write a namespace declaration.

C#

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

public class Sample {

  public static void Main() {

     XmlWriter writer = null;

     writer = XmlWriter.Create("sampledata.xml");

     // Write the root element.
     writer.WriteStartElement("book");

     // Write the xmlns:bk="urn:book" namespace declaration.
     writer.WriteAttributeString("xmlns","bk", null,"urn:book");

     // Write the bk:ISBN="1-800-925" attribute.
     writer.WriteAttributeString("ISBN", "urn:book", "1-800-925");

     writer.WriteElementString("price", "19.95");

     // Write the close tag for the root element.
     writer.WriteEndElement();

     // Write the XML to file and close the writer.
     writer.Flush();
     writer.Close();
  }
}

Remarks

This method writes out the attribute with a user defined namespace prefix and associates it with the given namespace. If localName is "xmlns" then this method also treats this as a namespace declaration. In this case, the ns argument can be null.

WriteAttributeString does the following:

• If the attribute value includes double or single quotes, they are replaced with " and ' respectively.

• If writing an xml:space attribute, the writer verifies the attribute value is valid. (Valid values are preserve or default.)

• If writing an xml:lang attribute, the writer does not verify that the attribute value is valid according to the W3C XML 1.0 recommendation.

For the asynchronous version of this method, see WriteAttributeStringAsync.

WriteAttributeString(String, String)

Source:

XmlWriter.cs

When overridden in a derived class, writes out the attribute with the specified local name and value.

C#

public void WriteAttributeString(string localName, string? value);

Parameters

localName

String

The local name of the attribute.

value

String

The value of the attribute.

Exceptions

InvalidOperationException

The state of writer is not WriteState.Element or writer is closed.

-or-

An XmlWriter method was called before a previous asynchronous operation finished. In this case, InvalidOperationException is thrown with the message "An asynchronous operation is already in progress."

ArgumentException

The xml:space or xml:lang attribute value is invalid.

Examples

The following example writes out a book.

C#

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

 public class Sample
 {
   private const string m_Document = "sampledata.xml";

   public static void Main() {

      XmlWriter writer = null;

      try {

        XmlWriterSettings settings = new XmlWriterSettings();
        settings.Indent = true;
        writer = XmlWriter.Create (m_Document, settings);

        writer.WriteComment("sample XML fragment");

        // Write an element (this one is the root).
        writer.WriteStartElement("book");

        // Write the namespace declaration.
        writer.WriteAttributeString("xmlns", "bk", null, "urn:samples");

        // Write the genre attribute.
        writer.WriteAttributeString("genre", "novel");

        // Write the title.
        writer.WriteStartElement("title");
        writer.WriteString("The Handmaid's Tale");
        writer.WriteEndElement();

        // Write the price.
        writer.WriteElementString("price", "19.95");

        // Lookup the prefix and write the ISBN element.
        string prefix = writer.LookupPrefix("urn:samples");
        writer.WriteStartElement(prefix, "ISBN", "urn:samples");
        writer.WriteString("1-861003-78");
        writer.WriteEndElement();

        // Write the style element (shows a different way to handle prefixes).
        writer.WriteElementString("style", "urn:samples", "hardcover");

        // Write the close tag for the root element.
        writer.WriteEndElement();

        // Write the XML to file and close the writer.
        writer.Flush();
        writer.Close();
      }

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

Remarks

WriteAttributeString does the following:

• If the attribute value includes double or single quotes, they are replaced with " and ' respectively.

• If writing an xml:space attribute, the writer verifies the attribute value is valid. (Valid values are preserve or default.)

• If writing an xml:lang attribute, the writer does not verify that the attribute value is valid according to the W3C XML 1.0 recommendation.

For the asynchronous version of this method, see WriteAttributeStringAsync.