I have written a chunk of XML parsing which works successfully provided I use an absolute path.
I now need to take an XMLNode as an argument and run an xpath against this.
Does anyone know how to do this?
I tried using relative XPath queries without any success!!
Should it be this hard??
It would help to see examples of XPath expressions that don't work as you think they should. Here are some possible causes (mistakes I frequently make).
Assume an XML document such as:
<A> <B> <C d='e'/> </B> <C/> <D xmlns="http://foo"/> </A> forgetting to remove the top-level slash ('/') representing the document:
document.XPathSelectElements("/A") // selects a single A node
document.XPathSelectElements("//B") // selects a single B node
document.XPathSelectElements("//C") // selects two C nodes
but
aNode.XPathSelectElements("/B") // selects nothing (this looks for a rootNode with name B) aNode.XPathSelectElements("B") // selects a B node bNode.XPathSelectElements("//C") // selects TWO C nodes - all descendants of the root node bNode.select(".//C") // selects one C node - all descendants of B forgetting namespaces.
aNode.XPathSelectElements("D") // selects nothing (D is in a different namespace from A) aNode.XPathSelectElements("[local-name()='D' and namespace-uri()='http://foo']") // one D node
(This is often a problem when the root node carries a prefixless namespace - easy to miss)
