XmlNamespaceManager.AddNamespace(String, String) Method

Definition

Adds the given namespace to the collection.

public:
 virtual void AddNamespace(System::String ^ prefix, System::String ^ uri);
public virtual void AddNamespace (string prefix, string uri);
abstract member AddNamespace : string * string -> unit
override this.AddNamespace : string * string -> unit
Public Overridable Sub AddNamespace (prefix As String, uri As String)

Parameters

prefix
String

The prefix to associate with the namespace being added. Use String.Empty to add a default namespace.

NoteIf the XmlNamespaceManager will be used for resolving namespaces in an XML Path Language (XPath) expression, a prefix must be specified. If an XPath expression does not include a prefix, it is assumed that the namespace Uniform Resource Identifier (URI) is the empty namespace. For more information about XPath expressions and the XmlNamespaceManager, refer to the SelectNodes(String) and SetContext(XmlNamespaceManager) methods.

uri
String

The namespace to add.

Exceptions

The value for prefix is "xml" or "xmlns".

The value for prefix or uri is null.

Examples

The following example uses XmlNamespaceManager to resolve namespaces in an XML fragment.

using System;
using System.Xml;

public class Sample
{

    public static void Main()
    {

        XmlTextReader reader = null;

        try
        {

            // Create the string containing the XML to read.
            String xmlFrag = "<book>" +
                           "<title>Pride And Prejudice</title>" +
                           "<author>" +
                           "<first-name>Jane</first-name>" +
                           "<last-name>Austen</last-name>" +
                           "</author>" +
                           "<curr:price>19.95</curr:price>" +
                           "<misc>&h;</misc>" +
                           "</book>";

            // Create an XmlNamespaceManager to resolve namespaces.
            NameTable nt = new NameTable();
            XmlNamespaceManager nsmgr = new XmlNamespaceManager(nt);
            nsmgr.AddNamespace(String.Empty, "urn:samples"); //default namespace
            nsmgr.AddNamespace("curr", "urn:samples:dollar");

            // Create an XmlParserContext.  The XmlParserContext contains all the information
            // required to parse the XML fragment, including the entity information and the
            // XmlNamespaceManager to use for namespace resolution.
            XmlParserContext context;
            String subset = "<!ENTITY h 'hardcover'>";
            context = new XmlParserContext(nt, nsmgr, "book", null, null, subset, null, null, XmlSpace.None);

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

            // Parse the file and display the node values.
            while (reader.Read())
            {
                if (reader.HasValue)
                    Console.WriteLine("{0} [{1}] = {2}", reader.NodeType, reader.Name, reader.Value);
                else
                    Console.WriteLine("{0} [{1}]", reader.NodeType, reader.Name);
            }
        }
        finally
        {
            if (reader != null)
                reader.Close();
        }
    }
} // End class
Imports System.Xml

Public Class Sample

    Public Shared Sub Main()

        Dim reader As XmlTextReader = Nothing

        Try

            ' Create the string containing the XML to read.
            Dim xmlFrag As String
            xmlFrag = "<book>" & _
                           "<title>Pride And Prejudice</title>" & _
                           "<author>" & _
                           "<first-name>Jane</first-name>" & _
                           "<last-name>Austen</last-name>" & _
                           "</author>" & _
                           "<curr:price>19.95</curr:price>" & _
                           "<misc>&h;</misc>" & _
                           "</book>"

            ' Create an XmlNamespaceManager to resolve namespaces.
            Dim nt As NameTable = New NameTable()
            Dim nsmgr As XmlNamespaceManager = New XmlNamespaceManager(nt)
            nsmgr.AddNamespace(String.Empty, "urn:samples") 'default namespace
            nsmgr.AddNamespace("curr", "urn:samples:dollar")

            ' Create an XmlParserContext.  The XmlParserContext contains all the information
            ' required to parse the XML fragment, including the entity information and the
            ' XmlNamespaceManager to use for namespace resolution.
            Dim context As XmlParserContext
            Dim subset As String = "<!ENTITY h 'hardcover'>"
            context = New XmlParserContext(nt, nsmgr, "book", Nothing, Nothing, subset, Nothing, Nothing, XmlSpace.None)

            ' Create the reader.
            reader = New XmlTextReader(xmlFrag, XmlNodeType.Element, context)

            ' Parse the file and display the node values.
            While (reader.Read())
                If (reader.HasValue) Then
                    Console.WriteLine("{0} [{1}] = {2}", reader.NodeType, reader.Name, reader.Value)
                Else
                    Console.WriteLine("{0} [{1}]", reader.NodeType, reader.Name)
                End If
            End While

        Finally
            If Not (reader Is Nothing) Then
                reader.Close()
            End If
        End Try
    End Sub
End Class

Remarks

XmlNamespaceManager does not check prefix and uri for conformance.

XmlReader checks names, including prefixes and namespaces, to ensure they are valid XML names according to the World Wide Web Consortium (W3C) Namespaces specification. XmlNamespaceManager is used internally by XmlReader, so to avoid a duplication of efforts, XmlNamespaceManager assumes all prefixes and namespaces are valid.

If the prefix and namespace already exist within the current scope, the new prefix and namespace pair will replace the existing prefix/namespace combination. The same prefix and namespace combination can exist across different scopes.

The following prefix/namespace pairs are added by default to the XmlNamespaceManager. They can be determined at any scope.

Prefix Namespace
xmlns http://www.w3.org/2000/xmlns/ (the xmlns prefix namespace)
xml http://www.w3.org/XML/1998/namespace (the XML namespace)
String.Empty String.Empty (the empty namespace). This value can be reassigned a different prefix. For example, xmlns="" defines the default namespace to be the empty namespace

Applies to

See also