How to query XElement with two namespaces

Question

I'm trying to find the inner text value of an element using LINQ-to-XML (an XElement object). I make my service call and get an XML response back that I've successfully loaded into an XElement object. I want to extract the inner text of one of the elements - however, every time I try to do this, I get a null result.

I feel like I'm missing something super-simple, but I'm fairly new to LINQ-to-XML. Any help is appreciated.

I'm trying to get the inner text value of the StatusInfo/Status element. Here's my XML document that's returned:

<feed xml:lang="en-us" xmlns="http://www.w3.org/2005/Atom">
  <title type="text">My Response</title>
  <id>tag:foo.com,2012:/bar/06468dfc-32f7-4650-b765-608f2b852f22</id>
  <author>
    <name>My Web Services</name>
  </author>
  <link rel="self" type="application/atom+xml" href="http://myServer/service.svc/myPath" />
  <generator uri="http://myServer" version="1">My Web Services</generator>
  <entry>
    <id>tag:foo.com,2012:/my-web-services</id>
    <title type="text" />
    <updated>2012-06-27T14:22:42Z</updated>
    <category term="tag:foo.com,2008/my/schemas#system" scheme="tag:foo.com,2008/my/schemas#type" />
    <content type="application/vnd.my.webservices+xml">
      <StatusInfo xmlns="tag:foo.com,2008:/my/data">
        <Status>Available</Status>  <!-- I want the inner text -->
      </StatusInfo>
    </content>
  </entry>
</feed>

Here's a snippet of code that I'm using to extract the value (which doesn't work):

    XElement root = XElement.Load(responseReader);
    XNamespace tag = "tag:foo.com,2008:/my/data";
    var status = (from s in root.Elements(tag + "Status")
                 select s).FirstOrDefault();

My status variable is always null. I've tried several variations on this, but to no avail. The part that's confusing me is the namespace -- tag and 2008 are defined. I don't know if I'm handling this correctly or if there's a better way to deal with this.

Also, I don't have control over the XML schema or the structure of the XML. The service I'm using is out of my control.

Thanks for any help!

Are you sure you want to query `root.Elements`? Based on the documentation, it seems to me that `root.Elements` only returns (direct) children of `root`, whereas your `` element is more deeply nested. — O. R. Mapper, Jun 27 '12 at 15:42
@O.R.Mapper stupid mistake on my part. If you add as an answer, I'll mark it as correct. Thanks! — David Hoerster, Jun 27 '12 at 16:14
ebpower has already added a suitable answer with a workaround :-) — O. R. Mapper, Jun 27 '12 at 18:27

score 2 · Accepted Answer · answered Jun 27 '12 at 16:53

2

Try Descendants() instead of Elements():

XElement x = XElement.Load(responseReader);
XNamespace ns = "tag:foo.com,2008:/my/data";
var status = x.Descendants(ns + "Status").FirstOrDefault().Value;

answered Jun 27 '12 at 16:53

Ed Power

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score 0 · Answer 2 · answered Jun 27 '12 at 17:08

There are 2 Namespaces in the feed:

the Atom namespace
the tag namespace

The outer xml needs to use the Atom namespace, while a portion of the inner xml needs to use the tag namespace. i.e.,

var doc = XDocument.Load(responseReader);
XNamespace nsAtom = "http://www.w3.org/2005/Atom";
XNamespace nsTag = "tag:foo.com,2008:/my/data";

// get all entry nodes / use the atom namespace
var entry = doc.Root.Elements(nsAtom + "entry");

// get all StatusInfo elements / use the atom namespace
var statusInfo = entry.Descendants(nsTag + "StatusInfo");

// get all Status / use the tag namespace
var status = statusInfo.Elements(nsTag + "Status");

// get value of all Status
var values = status.Select(x => x.Value.ToString()).ToList();

How to query XElement with two namespaces

2 Answers2

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