XPath query on XmlNode

[Claudio]

Hi
I'm trying to use XPath queries with streaming XML, but I cannot make
it working.
The solution I'm trying to implement is: create a XmlNode as soon as I
have a full XML element and use the SelectSingleNod e method with the
XPath query

Here is a test console application i wrote to better demonstrate my
issue and.. help you help me :)

--------------
using System;
using System.Text;
using System.IO;
using System.Xml;
using System.Diagnost ics;

class xpath
{
static void Main(string[] args)
{
//INITIALIZATION
//create the xml reader
Stream stream = new MemoryStream(
Encoding.UTF8.G etBytes(
"<iq><bind xmlns='urn:long :namespace'><ji d>MYVALUE</jid></bind></iq>")
, false);
XmlReaderSettin gs xmlRsettings = new XmlReaderSettin gs();
xmlRsettings.Co nformanceLevel = ConformanceLeve l.Fragment;
xmlRsettings.Ig noreComments = true;
XmlReader xmlReader = XmlReader.Creat e(stream, xmlRsettings);

//move to the first element (<iq>)
xmlReader.Read( );
XmlDocument doc = new XmlDocument();
//END INITIALIZATION

XmlNode node = doc.ReadNode(xm lReader);

//here I would like to read MYVALUE
//this is OK

Debug.WriteLine (node.ChildNode s[0].ChildNodes[0].ChildNodes[0].Value);
//but I'd rather using a XPath query like
XmlNode val = node.SelectSing leNode("iq/bind/jid/text()");
Debug.WriteLine (val == null ? "null" : val.Value);
}
}

--------------
Any idea on what I'm doing wrong? Do you see other approaches?
Thank you

[Martin Honnen]

Claudio wrote:

Stream stream = new MemoryStream(
Encoding.UTF8.G etBytes(
"<iq><bind xmlns='urn:long :namespace'><ji d>MYVALUE</jid></bind></iq>")
, false);

The bind element and its child jid element are in the namespace with the
URI urn:long:namesp ace which means to do XPath on that you nead an
XmlNamespaceMan ager instance, bind a prefix to the URI, use that prefix
in your XPath expressions and pass the namespace manager as the second
argument of SelectNodes/SelectSingleNod e e.g.

XmlNamespaceMan ager namespaceManage r = new
XmlNamespaceMan ager(doc.NameTa ble);
namespaceManage r.AddNamespace( "pf", "urn:long:names pace");
XmlNode val = node.SelectSing leNode("pf:bind/pf:jid/text()",
namespaceManage r);
Note that the XPath expression needed to be corrected in your post.

--

Martin Honnen --- MVP XML
http://JavaScript.FAQTs.com/

[Claudio]

Thank you very much for the quick and perfect reply!

Martin Honnen wrote:

The bind element and its child jid element are in the namespace with the
URI urn:long:namesp ace which means to do XPath on that you nead an
XmlNamespaceMan ager instance, bind a prefix to the URI, use that prefix
in your XPath expressions and pass the namespace manager as the second
argument of SelectNodes/SelectSingleNod e e.g.

XmlNamespaceMan ager namespaceManage r = new
XmlNamespaceMan ager(doc.NameTa ble);
namespaceManage r.AddNamespace( "pf", "urn:long:names pace");
XmlNode val = node.SelectSing leNode("pf:bind/pf:jid/text()",
namespaceManage r);
Note that the XPath expression needed to be corrected in your post.

--

Martin Honnen --- MVP XML
http://JavaScript.FAQTs.com/