Why doesn't this XPath query returns any nodes?

Question

I'm querying Sharepoint server-side and getting back results as Xml. I want to slim down the Xml into something more lightweight before sending it to jQuery through a WebMethod.

However my XPath query isn't working. I thought the following code would return all Document nodes, but it returns nothing. I've used XPath a little before, I thought //Document do the trick.

C# XPath query

XmlDocument xmlResults = new XmlDocument();
xmlResults.LoadXml(xml); // XML is a string containing the XML source shown below
XmlNodeList results = xmlResults.SelectNodes("//Document");

XML being queried

<ResponsePacket xmlns="urn:Microsoft.Search.Response">
      <Response domain="QDomain">
            <Range>
                  <StartAt>1</StartAt>
                  <Count>2</Count>
                  <TotalAvailable>2</TotalAvailable>
                  <Results>
                        <Document relevance="126" xmlns="urn:Microsoft.Search.Response.Document">
                              <Title>Example 1.doc</Title>
                              <Action>
                                    <LinkUrl size="32256" fileExt="doc">http://hqiis99/Mercury/Mercury documents/Example 1.doc</LinkUrl>
                              </Action>
                              <Description />
                              <Date>2010-08-19T14:44:56+01:00</Date>
                        </Document>
                        <Document relevance="31" xmlns="urn:Microsoft.Search.Response.Document">
                              <Title>Mercury documents</Title>
                              <Action>
                                    <LinkUrl size="0" fileExt="aspx">http://hqiis99/mercury/Mercury documents/Forms/AllItems.aspx</LinkUrl>
                              </Action>
                              <Description />
                              <Date>2010-08-19T14:49:39+01:00</Date>
                        </Document>
                  </Results>
            </Range>
            <Status>SUCCESS</Status>
      </Response>
</ResponsePacket>

The XPath would return all Document nodes in the source XML file. Are you sure they are there and if so are you sure your results variable is empty? — Oded
– Oded, Commented Aug 20, 2010 at 10:05
The xml string variable contains the XML shown above, I've updated my source code with a comment to communicate this — Peter Bridger
– Peter Bridger, Commented Aug 20, 2010 at 10:07

Black Light · Accepted Answer · 2013-09-12 08:19:29Z

11

You're trying to select Document elements which don't have a namespace... whereas the default namespace is actually "urn:Microsoft.Search.Response" here.

I think you want something like this:

XmlDocument xmlResults = new XmlDocument();
xmlResults.LoadXml(xml);
XmlNamespaceManager manager = new XmlNamespaceManager(xmlResults.NameTable);
manager.AddNamespace("ns", "urn:Microsoft.Search.Response.Document");
XmlNodeList results = xmlResults.SelectNodes("//ns:Document", manager);

This finds two elements.

If you can use LINQ to XML instead, it makes it all somewhat easier:

XDocument results = XDocument.Parse(xml);
XNamespace ns = "urn:Microsoft.Search.Response.Document";
var documents = results.Descendants(ns + "Document");

I love LINQ to XML's namespace handling :)

edited Sep 12, 2013 at 8:19

Black Light

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answered Aug 20, 2010 at 10:05

Jon Skeet

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6 Comments

Oded Over a year ago

He has an additional namespace: urn:Microsoft.Search.Response.Document

Peter Bridger Over a year ago

I've no experience with Xml namespaces, what's the next step?

Jon Skeet Over a year ago

@Peter: Do you definitely want to use XPath here? LINQ to XML would make this easier, if you can use that.

Peter Bridger Over a year ago

@Jon-Skeet LINQ to XML is fine - my initials thoughts were that using XPath would be easier :) It's seems not! So feel free to update your answer with an LINQ to XML example and if it works I'll accept it.

Jon Skeet Over a year ago

@Oded: Thanks - I missed that before, and got confused when it didn't find anything :(

|

mnield · Accepted Answer · 2010-08-23 14:34:16Z

3

Alternatively, you could try the following and ignore the namespaces:

XmlDocument xmlResults = new XmlDocument();
xmlResults.LoadXml(xmlString);
XmlNodeList results = xmlResults.SelectNodes("//*[local-name()='Document']");

answered Aug 23, 2010 at 14:34

mnield

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