Substring XPath

[Derek Hart]

This is probably so simple. I am doing a SelectSingleNode to get the value
from an XPath statement, and I simply want the 3 leftmost characters. I
cannot get the syntax to work:

//Client/Names/Name[@nameaddresssource_id='3']/@display_name

So I have tried:

substring(//Client/Names/Name[@nameaddresssource_id='3']/@display_name,1,3)

What is the correct syntax?

[Bjoern Hoehrmann]

* Derek Hart wrote in microsoft.public.dotnet.xml:

This is probably so simple. I am doing a SelectSingleNode to get the value
from an XPath statement, and I simply want the 3 leftmost characters.

SelectSingleNode selects a single node; a 3 character string is not a
node, so you cannot do this using SelectSingleNode. You would need a
different method that supports this kind of query, I am not sure your
version of the .NET Framework has one. It might be easier to select
the attribute node and retrieve the 3 characters using native String
operations.
--
Björn Höhrmann · mailto:bj****@hoehrmann.de · http://bjoern.hoehrmann.de
Weinh. Str. 22 · Telefon: [phone] · http://www.bjoernsworld.de
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[Martin Honnen]

Derek Hart wrote:

This is probably so simple. I am doing a SelectSingleNode to get the value
from an XPath statement, and I simply want the 3 leftmost characters. I
cannot get the syntax to work:

//Client/Names/Name[@nameaddresssource_id='3']/@display_name

So I have tried:

substring(//Client/Names/Name[@nameaddresssource_id='3']/@display_name,1,3)

What is the correct syntax?

The problem is that SelectSingleNode and SelectNodes needs an XPath
expression that selects a node set while your XPath returns a string so
you need to use a different API, you could use the Evaluate method on an
XPathNavigator, see
<http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfSystemXmlXPathXPathNavigatorClassEvaluateTopi c1.asp>

Or use SelectSingleNode and then use .NET string operations on the
attribute's Value property.

--

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