XmlNode.SelectNodes Method (String, XmlNamespaceManager) (System.Xml)

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.NET Framework Class Library
XmlNode.SelectNodes Method (String, XmlNamespaceManager)

Selects a list of nodes matching the XPath expression. Any prefixes found in the XPath expression are resolved using the supplied XmlNamespaceManager.

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

Visual Basic
Public Function SelectNodes ( _
	xpath As String, _
	nsmgr As XmlNamespaceManager _
) As XmlNodeList
C#
public XmlNodeList SelectNodes(
	string xpath,
	XmlNamespaceManager nsmgr
)
Visual C++
public:
XmlNodeList^ SelectNodes(
	String^ xpath, 
	XmlNamespaceManager^ nsmgr
)
F#
member SelectNodes : 
        xpath:string * 
        nsmgr:XmlNamespaceManager -> XmlNodeList 

Parameters

xpath
Type: System.String
The XPath expression.
nsmgr
Type: System.Xml.XmlNamespaceManager
An XmlNamespaceManager to use for resolving namespaces for prefixes in the XPath expression.

Return Value

Type: System.Xml.XmlNodeList
An XmlNodeList containing a collection of nodes matching the XPath query.
Exceptions

Exception Condition
XPathException

The XPath expression contains a prefix which is not defined in the XmlNamespaceManager.

Remarks

XPath expressions can include namespaces. Namespace resolution is supported using the XmlNamespaceManager. If the XPath expression includes a prefix, the prefix and namespace URI pair must be added to the XmlNamespaceManager.

Note Note

If the XPath expression does not include a prefix, it is assumed that the namespace URI is the empty namespace. If your XML includes a default namespace, you must still add a prefix and namespace URI to the XmlNamespaceManager; otherwise, you will not get any nodes selected. For more information, see Select Nodes Using XPath Navigation.

For example, if you had the following XML:

 <bookstore xmlns="http://www.lucernepublishing.com">
  <book>
    <title>Pride And Prejudice</title>
  </book>
 </bookstore>

The following C# code selects all book nodes:

 XmlNamespaceManager nsmgr = new XmlNamespaceManager(doc.NameTable);
 nsmgr.AddNamespace("ab", "http://www.lucernepublishing.com");
 XmlNodeList nodelist = doc.SelectNodes("//ab:book", nsmgr);
Note Note

A common issue when formulating XPath expressions is how to include a single quote (') or double quote (") in the expression. If you have to search for a value that includes a single quote, you must enclose the string in double quotes. If you need to search for a value that includes a double quote, you must enclose the string in single quotes.

For example, suppose you have the following XML:

 <bookstore xmlns="http://www.lucernepublishing.com">
   <book>
     <title>&apos;Emma&apos;</title>
   </book>
 </bookstore>

The following Visual Basic code selects an element that contains single quotes:

 Dim nsmgr As XmlNamespaceManager = New XmlNamespaceManager(doc.NameTable)
 nsmgr.AddNamespace("ab", "http://www.lucernepublishing.com")
 nodeList = root.SelectNodes("//ab:book[contains(ab:title,""'Emma'"")]", nsmgr)

This method is a Microsoft extension to the Document Object Model (DOM).

The XmlNodeList object returned by this method will be valid while the underlying document remains unchanged. If the underlying document changes, unexpected results may be returned (no exception will be thrown).

Examples

The following example displays the values of each of the ISBN attributes.

Visual Basic

Imports System
Imports System.IO
Imports System.Xml

public class Sample

  public shared sub Main()

      Dim doc as XmlDocument = new XmlDocument()
      doc.Load("booksort.xml")

      'Create an XmlNamespaceManager for resolving namespaces.
      Dim nsmgr as XmlNamespaceManager = new XmlNamespaceManager(doc.NameTable)
      nsmgr.AddNamespace("bk", "urn:samples")

      'Select and display the value of all the ISBN attributes.
      Dim nodeList as XmlNodeList 
      Dim root as XmlElement = doc.DocumentElement
      nodeList = root.SelectNodes("/bookstore/book/@bk:ISBN", nsmgr)
      Dim isbn as XmlNode
      for each isbn in nodeList
        Console.WriteLine(isbn.Value)
      next

  end sub
end class


C#

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

public class Sample
{
  public static void Main()
  {

      XmlDocument doc = new XmlDocument();
      doc.Load("booksort.xml");

      //Create an XmlNamespaceManager for resolving namespaces.
      XmlNamespaceManager nsmgr = new XmlNamespaceManager(doc.NameTable);
      nsmgr.AddNamespace("bk", "urn:samples");

      //Select and display the value of all the ISBN attributes.
      XmlNodeList nodeList;
      XmlElement root = doc.DocumentElement;
      nodeList = root.SelectNodes("/bookstore/book/@bk:ISBN", nsmgr);
      foreach (XmlNode isbn in nodeList){
        Console.WriteLine(isbn.Value);
      }

   }

}


Visual C++

#using <System.Xml.dll>

using namespace System;
using namespace System::IO;
using namespace System::Xml;
using namespace System::Collections;
int main()
{
   XmlDocument^ doc = gcnew XmlDocument;
   doc->Load( "booksort.xml" );

   // Create an XmlNamespaceManager for resolving namespaces.
   XmlNamespaceManager^ nsmgr = gcnew XmlNamespaceManager( doc->NameTable );
   nsmgr->AddNamespace( "bk", "urn:samples" );

   // Select and display the value of all the ISBN attributes.
   XmlNodeList^ nodeList;
   XmlElement^ root = doc->DocumentElement;
   nodeList = root->SelectNodes( "/bookstore/book/@bk:ISBN", nsmgr );
   IEnumerator^ myEnum = nodeList->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      XmlNode^ isbn = safe_cast<XmlNode^>(myEnum->Current);
      Console::WriteLine( isbn->Value );
   }
}



The example uses the file, booksort.xml, as input.



<?xml version="1.0"?>
<!-- A fragment of a book store inventory database -->
<bookstore xmlns:bk="urn:samples">
  <book genre="novel" publicationdate="1997" bk:ISBN="1-861001-57-8">
    <title>Pride And Prejudice</title>
    <author>
      <first-name>Jane</first-name>
      <last-name>Austen</last-name>
    </author>
    <price>24.95</price>
  </book>
  <book genre="novel" publicationdate="1992" bk:ISBN="1-861002-30-1">
    <title>The Handmaid's Tale</title>
    <author>
      <first-name>Margaret</first-name>
      <last-name>Atwood</last-name>
    </author>
    <price>29.95</price>
  </book>
  <book genre="novel" publicationdate="1991" bk:ISBN="1-861001-57-6">
    <title>Emma</title>
    <author>
      <first-name>Jane</first-name>
      <last-name>Austen</last-name>
    </author>
    <price>19.95</price>
  </book>
  <book genre="novel" publicationdate="1982" bk:ISBN="1-861001-45-3">
    <title>Sense and Sensibility</title>
    <author>
      <first-name>Jane</first-name>
      <last-name>Austen</last-name>
    </author>
    <price>19.95</price>
  </book>
</bookstore>


Version Information

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1
Platforms

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
See Also

Reference