XML Document SelectSingleNode returns null

Question

I am trying to read XML from stream reader and am also getting response XML. But when i try to read its nodes it is always returning null.

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Answer 1

The problem is that you're asking for a RateQuote element without a namespace - whereas the RateQuote element is actually in the namespace with URI http://ratequote.usfnet.usfc.com/v2/x1.

You can either use an XmlNamespaceManager to address the namespace within your XPath, or use LINQ to XML which has very simple namespace handling:

var document = XDocument.Load(stream);
XNamespace ns = "http://ratequote.usfnet.usfc.com/v2/x1";
XElement rateQuote = document.Root.Element(ns + "RateQuote");

Personally I would use LINQ to XML if you possibly can - I find it much more pleasant to use than XmlDocument. You can still use XPath if you want of course, but I personally prefer to use the querying methods.

EDIT: Note that the namespace defaulting applies to child elements too. So to find the TOTAL_COST element you'd need:

XElement cost = document.Root
                        .Element(ns + "RateQuote")
                        .Element(ns + "TOTAL_COST");