How Do I Use SelectSingleNode in C# to Retrieve XML Elements with Namespaces?

Using SelectSingleNode to handle XML namespaces in C#

A common problem when accessing XML elements using SelectSingleNode is that it may return null if the tag contains an XML namespace. This problem occurs because SelectSingleNode only considers elements in the default namespace by default.

Consider the sample XML structure provided:

<code class="language-xml"><project defaulttargets="Build" toolsversion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003"><itemgroup><compile include="clsWorker.cs"></compile></itemgroup></project></code>

When loading this XML into XmlDocument and trying to retrieve the "Compile" element:

<code class="language-csharp">XmlDocument xmldoc = new XmlDocument();
xmldoc.LoadXml(Xml);

XmlNode node = xmldoc.SelectSingleNode("//Compile"); // 返回null</code>

The result will be null because the "Compile" element is located in "https://www.php.cn/link/55a51239dc6fe8cf8c09ec91f36f5250.

Solution: Use XmlNamespaceManager

To solve this problem, we need to use XmlNamespaceManager to specify the correct namespace when performing the SelectSingleNode operation:

<code class="language-csharp">XmlNamespaceManager ns = new XmlNamespaceManager(xmldoc.NameTable);
ns.AddNamespace("msbld", "http://schemas.microsoft.com/developer/msbuild/2003");
XmlNode node = xmldoc.SelectSingleNode("//msbld:Compile", ns);</code>

XmlNamespaceManager allows us to map the namespace prefix "msbld" to an actual namespace URI. With this approach, we can now successfully retrieve the "Compile" element using the modified SelectSingleNode syntax.

The above is the detailed content of How Do I Use SelectSingleNode in C# to Retrieve XML Elements with Namespaces?. For more information, please follow other related articles on the PHP Chinese website!