Information Obtained from the XmlNamespaceManager 

The following table shows that once information has been placed in the XmlNamespaceManager, there are several methods and properties available to perform tasks that set or retrieve information.

The following example shows how the LookupPrefix method is used when writing an attribute. It uses the WriteStartAttribute method to start the attribute, and the LookupPrefix is used to look up the prefix for the urn:samples namespaceURI, then uses that prefix in the WriteStartAttribute when writing the ISBN attribute:

Dim prefix As String = nsMgr.LookupPrefix("urn:samples")
writer.WriteStartAttribute(prefix, "ISBN", "urn:samples")

XmlNameTable nt = new XmlNameTable();
XmlNamespaceManager nsMgr = new XmlNamespaceManager(nt);
nsMgr.AddNamespace("bk","urn:samples");string prefix = writer nsMgr.LookupPrefix("urn:samples");
writer.WriteStartAttribute(prefix, "ISBN", "urn:samples");

The following example uses LookupPrefix to find the prefix defined on an element.

writer.WriteStartElement("root", "book")
writer.WriteStartElement("x", "node", "author")
s = writer.LookupPrefix("author")
CError.Compare(s, "x", "Error in nested element")
writer.WriteEndElement()
s = writer.LookupPrefix("book")
CError.Compare(s, Nothing, "Error in root element")
writer.WriteEndElement()

writer.WriteStartElement("root", "book");
writer.WriteStartElement("x", "node", "author");
s = writer.LookupPrefix("author");
CError.Compare(s, "x", "Error in nested element");
writer.WriteEndElement();
s = writer.LookupPrefix("book");
CError.Compare(s, null, "Error in root element");
writer.WriteEndElement();

Output

<root xmlns="book">
  <x:node xmlns:x="author" /> 
</root>

The following example shows how to add a namespace using the AddNamespace method, and how to give it specific scope using the PushScope and PopScope methods.

Public Sub Main()
        Dim nametable As NameTable = New NameTable()
        Dim nsm As XmlNamespaceManager = New XmlNamespaceManager(nametable)
        ' Add a default namespace.
        nsm.AddNamespace(String.Empty, "www.microsoft.com")
        nsm.AddNamespace("msbooks", "www.microsoft.com/books")
        'Push the namespace scope on the stack.
        nsm.PushScope()
        nsm.AddNamespace("msstore", "www.microsoft.com/store")
        checkns(nsm)
        nsm.PopScope()
        checkns(nsm)

        Dim response As String = Console.ReadLine

End Sub

Public Sub checkns(ByVal nsm As XmlNamespaceManager)
        If nsm.HasNamespace(String.Empty) Then
            Console.WriteLine("DefaultNamespace in scope")
        Else
            Console.WriteLine("DefaultNamespace not in scope")
        End If
        If nsm.HasNamespace("msstore") Then
            Console.WriteLine("www.microsoft.com/store"" in scope")
        Else
            Console.WriteLine("www.microsoft.com/store not in scope")
        End If
        If nsm.HasNamespace("msbooks") Then
            Console.WriteLine("www.microsoft.com/books in scope")
        Else
            Console.WriteLine("www.microsoft.com/books not in scope")
        End If
End Sub
 

XmlNameTable nt = new XmlNameTable();
XmlNamespaceManager nsmanager = new XmlNamespaceManager(nt);
//Add a default namespace.
nsmanager.AddNamespace (String.Empty, "www.microsoft.com"); 
nsmanager.AddNamespace ("msbooks", "www.microsoft.com/books");
nsmanager.PushScope();
nsmanager.AddNamespace ("msstore", "www.microsoft.com/store");
checkns(nsmanager);
nsmanager.PopScope();
checkns(nsmanager);

checkns(XmlNamespaceManager nsm)
{
    if (nsm.HasNamespace(String.Empty))
        Console.WriteLine("DefaultNamespace in scope");
    else
        Console.WriteLine("DefaultNamespace not in scope");
    if (nsm.HasNamespace("msstore"))
        Console.WriteLine(""www.microsoft.com/store"" in scope");
    else
        Console.WriteLine(""www.microsoft.com/store"" not in scope");
    if (nsm.HasNamespace("msbooks"))
        Console.WriteLine(""www.microsoft.com/books"" in scope");
    else
        Console.WriteLine(""www.microsoft.com/books"" not in scope");
}

Output

DefaultNamespace not in scope
www.microsoft.com/store" in scope
www.microsoft.com/books not in scope
DefaultNamespace in scope
www.microsoft.com/store not in scope
www.microsoft.com/books in scope

The following example enumerates all of the prefixes in the current scope, which also lists the additional three namespaces and prefix pairs. These three default namespace and prefix pairs are automatically added to the namespace manager on creation.

Dim nametable As NameTable = New NameTable()
Dim nsm As XmlNamespaceManager = New XmlNamespaceManager(nametable)
'Add a default namespace.
nsm.AddNamespace("xmlabc", "www.microsoft.com")
Dim prefix As String
For Each prefix In nsm
    Console.WriteLine("Namespace:{0}, Prefix:{1}", nsm.LookupNamespace(nsm.NameTable.Get(prefix)), prefix)
Next

NameTable nametable = new NameTable();
XmlNamespaceManager nsm = new XmlNamespaceManager(nametable);
//Add a default namespace.
nsm.AddNamespace("xmlabc", "www.microsoft.com"); 
foreach (String prefix in nsm)
    {
        Console.WriteLine("Namespace:{0}, Prefix:{1}",nsm.LookupNamespace(nsm.NameTable.Get(prefix)), prefix);
    }

Output

Namespace:https://www.w3.org/XML/1998/namespace, Prefix:xml
Namespace:https://www.w3.org/2000/xmlns/, Prefix:xmlns 
Namespace:, Prefix: 
Namespace:www.microsoft.com, Prefix:xmlabc

See Also

Concepts

Namespaces in an XML Document
Namespace Declarations
Default Namespaces
Namespace Declaration Scope
Manage Namespaces Using the XmlNamespaceManager