Question

I have XML something like this:

<?xml version="1.0"?>
<a xmlns="http://mynamespace">
  <b>
    <c val="test" />
  <b>
</a>

And I am trying to find the value of the ‘val’ attribute on the ‘c’ tag with something like this:

XmlDocument doc = new XmlDocument();
doc.Load("myxml.xml");

nsMgr = new XmlNamespaceManager(doc.NameTable);
nsMgr.AddNamespace(@"mns", "http://mynamespace");

XPathNavigator root = doc.CreateNavigator();

foreach (XPathNavigator nav in root.Select("//mns:c", nsMgr))
{
    string val = nav.GetAttribute("val", NS);

    Console.WriteLine("val == "+val);
}

My problem is that GetAttribute always returns as an empty string. What am I missing?

---

Update:

It seems I can fix this by passing an empty string into GetAttribute, i.e.

string val = nav.GetAttribute("val", "");

My question is therefore now: why does this work? Why does ‘val’ not belong to my namespace despite the XML having been validated against a schema which requires the ‘val’ attribute (I accidentally omitted this step in my above sample code, but I am validating the XML).

Answer 1

Default namespace declarations do not apply to attributes so that attribute named ‘val’ is in no namespace and if you want to access it then you need to access it without using a namespace.
The only way to put an attribute in a namespace is by giving it a qualified name with a prefix and local name (e.g. pf:val) where the prefix is bound to a namespace (e.g. xmlns:pf=”http://example.com/foo”).