How to read an XML document in C# with a namespace that has no associated prefix

Question

I am trying to read OSIS formatted documents. I have cut the document down to a simple fragment:

<?xml version="1.0" encoding="utf-8"?>
<osis xmlns="http://www.bibletechnologies.net/2003/OSIS/namespace">
  <osisText osisRefWork="Bible" osisIDWork="kjv" xml:lang="en">
  </osisText>
</osis>

I try to read it with this sample code from the MSDN documentation:

XPathDocument document = new XPathDocument("osis.xml");
XPathNavigator navigator = document.CreateNavigator();
XPathNodeIterator nodes = navigator.Select("/osis/osisText");

while (nodes.MoveNext())
{
    Console.WriteLine(nodes.Current.Name);
}

The problem is that the selection contains no nodes and throws no exception. Since the code discards the root tag, I can't read the document. If I remove the xmlns="http://www.bibletechnologies.net/2003/OSIS/namespace" from the root osis tag, it works just fine. The offensive URL returns a 404 code, but otherwise I see nothing wrong with this XML. Can someone explain why this code won't read the document? What options do I have besides hand editing every document before trying to load it?

That XML looks pretty well formed to me. What makes you think it is malformed? — leppie
– leppie, Commented Oct 25, 2011 at 5:09

harpo · Accepted Answer · 2011-10-25 14:43:03Z

9

Your XPath expression is missing a namespace prefix.

The element that you're trying to select has a namespace URI of http://www.bibletechnologies.net/2003/OSIS/namespace, and XPath will not match these nodes using paths with an empty namespace URI.

I tested this revision in .NET 2.0 and it found the node as expected.

XPathDocument document = new XPathDocument("osis.xml");
XPathNavigator navigator = document.CreateNavigator();

XmlNamespaceManager xmlns = new XmlNamespaceManager(navigator.NameTable);
xmlns.AddNamespace("osis", "http://www.bibletechnologies.net/2003/OSIS/namespace");

XPathNodeIterator nodes = navigator.Select("/osis:osis/osis:osisText", xmlns);

edited Oct 25, 2011 at 14:43

answered Oct 25, 2011 at 5:13

harpo

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4 Comments

J Edward Ellis Over a year ago

XML is pretty simple until you add namespaces. The actual osis node is:<osis xmlns="bibletechnologies.net/2003/OSIS/namespace" xmlns:xsi="w3.org/2001/XMLSchema-instance" xsi:schemaLocation="bibletechnologies.net/2003/OSIS/namespace bibletechnologies.net/osisCore.2.1.1.xsd">. Do I need to add something else to the namespace manager?

harpo Over a year ago

@JEdwardEllis, no... and I overlooked that you already had created a navigator. Yeah, you have to get into the zen of namespaces to minimize frustration. It can be ugly sometimes, but I learned from dealing with EPUBs (which use multiple namespaces) that you can't fight it. Good luck.

J Edward Ellis Over a year ago

Is there a good resource for learning about XML namespaces? I hate stumbling around in the dark.

harpo Over a year ago

If you're using .NET, the framework documentation is actually pretty good, especially since it's usually geared towards usage in applications. I read XML in a Nutshell in 2004 or so, and much of it still holds true (certainly the parts about namespaces, anyway). The zvon tutorial is still a good starting reference for XPath.

Daniel · Accepted Answer · 2011-10-25 05:13:32Z

0

You can read the file to a string, replace the namespace in memory, and then load it using a string stream:

string s;
using(var reader = File.OpenText("osis.xml"))
{
    s = reader.ReadToEnd();
}
s = s.Replace("xmlns=\"http://www.bibletechnologies.net/2003/OSIS/namespace\"", "");
Stream stream = new MemoryStream(Encoding.ASCII.GetBytes(s));
XPathDocument document = new XPathDocument("stream");
// Rest of the code

answered Oct 25, 2011 at 5:13

Daniel

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2 Comments

John Saunders Over a year ago

-1: as with most cases of pretending that XML is just a string format, this fails. What if, instead, the document said xmlns:x="http://www.bibletechnologies.net/2003/OSIS/namespace"? What if it used "y" as a prefix? What if there were multiple namespace declarations, for the same namespace, but with different prefixes?

Blue Clouds Over a year ago

@JohnSaunders did you find an answer?

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