XML SelectSingleNode in xmlns default namespace which seems to have some other value in it-CodePudding

<?xml version="1.0" encoding="UTF-8"?>
<MyRootElement xmlns="urn:MyNamespaceUri_1">
  <Color>
    <Name>Primary</Name>
    <ID>1</ID>
    <Description>Red</Description>    
    <Status>In Use</Status>    
    <Reference xmlns="urn:MyNamespaceUri_2">
      <ColorCode>3</ColorCode>      
      <ID>1616</ID>
    </Reference>
  </Color>
</MyRootElement>

I am trying to extract the value of ID element under Reference element using the following code and it SelectSingleNode call returns null

XmlNamespaceManager nsmgr = new XmlNamespaceManager(myXmlDoc.NameTable);
nsmgr.AddNamespace(String.Empty, "urn:MyNamespaceUri_1");

XmlNode idXml = myXmlDoc.SelectSingleNode("/MyRootElement/Color/Reference/ID", nsmgr);
var colorIdValue = idXml.InnerText;

.Net fiddle, https://dotnetfiddle.net/BA1AYu

CodePudding user response：

In order to find the node, you have to register the namespaces correctly, e.g.:

XmlNamespaceManager nsmgr = new XmlNamespaceManager(xmlDoc.NameTable);
nsmgr.AddNamespace("ns1", "urn:MyNamespaceUri_1");
nsmgr.AddNamespace("ns2", "urn:MyNamespaceUri_2");

XmlNode idXml = xmlDoc.SelectSingleNode("/ns1:MyRootElement/ns1:Color/ns2:Reference/ns2:ID", nsmgr);

if (idXml != null)
    Console.WriteLine(idXml.OuterXml);
else
    Console.WriteLine("NOT FOUND");

Please note that both namespaces are registered with a name that is also used as a prefix in the query. If you run the query, the output is:

<ID xmlns="urn:MyNamespaceUri_2">1616</ID>