Question

What am I doing wrong with this XPath query? Within the feed tag, there are multiple entry tags. The XML is valid, and so is the generated XPath query, I have tested both together with a tool called XPath Visualizer.

THe call to iterator.MoveNext() returns false, and after the operation the iterator is still on the root node. Am I missing something obvious here?

var stringReader = new StringReader(importData.Trim());

        var xpathDoc = new XPathDocument(stringReader);

        XPathNavigator xPathNav = xpathDoc.CreateNavigator();

        string xPathString = "//" + masterNode; // Evaluates to '//entry'

        XPathExpression xPathExpr = xPathNav.Compile(xPathString);

        XPathNodeIterator iterator = xPathNav.Select(xPathExpr);

        while (iterator.MoveNext())
        {
           ....

Example XML

<?xml version="1.0" encoding="UTF-8"?>
            <feed xmlns="http://www.w3.org/2005/Atom" xmlns:g="http://base.google.com/ns/1.0">
                <title>Test</title>
                <link rel="self" href="http://store.Test.com"/>
                <updated>2012-02-07T11:15:04Z</updated>
                <author>
                    <name>Test</name>
                </author>
                <id>tag:000000</id>
    <entry>
        <title><![CDATA[Example 7500cl]]></title>
        <link><![CDATA[http://store.test.com/example-75cl/]]></link>
        <description><![CDATA[example descr........]]></description>
    </entry>

Answer 1

The problem is with namespaces – there aren’t any entry elements without a namespace – the element you can see has the “http://www.w3.org/2005/Atom” namespace inherited from the root.

Personally I’d use LINQ to XML for this instead, but if you must use XPath, you’ll need to use a namespace manager to find elements with a particular namespace. A search for “xpath namespace .net” within Stack Overflow will give you lots of hits with options.

The LINQ to XML code would look like this:

XDocument doc = XDocument.Parse(importData.Trim());
XNamespace ns = "http://www.w3.org/2005/Atom";
var entries = doc.Descendants(ns + "entry");
foreach (var entry in entries)
{
    ...
}