Navigating XML with Default Namespaces in C# using XPath
Working with XML documents containing default namespaces often requires careful handling of XPath expressions to correctly select nodes. A common mistake is omitting namespace prefixes, leading to empty result sets.
This issue is resolved by explicitly incorporating the namespace into your XPath query. While an XPathNavigator
isn't strictly required, the SelectNodes
or SelectSingleNode
methods are sufficient.
The crucial step is creating an XmlNamespaceManager
. The following example demonstrates this:
XmlElement el = ...; //TODO: Obtain your XmlElement XmlNamespaceManager nsmgr = new XmlNamespaceManager(el.OwnerDocument.NameTable); nsmgr.AddNamespace("x", el.OwnerDocument.DocumentElement.NamespaceURI); var nodes = el.SelectNodes("/x:outerelement/x:innerelement", nsmgr);
This code snippet first initializes an XmlNamespaceManager
using the NameTable
from the XML document's root. It then registers the default namespace of the root element with the prefix "x". Finally, SelectNodes
is called with the XPath expression now including the "x" prefix, enabling the selection of the target nodes. Remember to replace the //TODO
comment with the code to obtain your XmlElement
.
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