Question

Consider the following XML:

<SomeRoot>
  <SomeElement>
    <SomeThing>25</SomeThing>
    <SomeOther>Cat</SomeOther>
  </SomeElement>
  <SomeElement>
    <SomeThing>46</SomeThing>
    <SomeOther>Dog</SomeOther>
  </SomeElement>
  <SomeElement>
    <SomeThing>83</SomeThing>
    <SomeOther>Bat</SomeOther>
  </SomeElement>
  <SomethingElse>Unrelated to the SomeElements above</SomethingElse>
</SomeRoot>

I want to select SomeThing where SomeOther = 'Cat'. The following C# code throws a null reference exception:

xmlDoc = new XmlDocument();
this.path = path;
// Path is passed elsewhere

Console.WriteLine(xmlDoc.SelectSingleNode("/SomeRoot/SomeElement/SomeThing[../SomeOther='Cat']").InnerText);

What is the correct XPath syntax to use here?

Answer 1

You are missing the load

var xmlDoc = new XmlDocument();
xmlDoc.Load(path);
Console.WriteLine(xmlDoc.SelectSingleNode("/SomeRoot/SomeElement/SomeThing[../SomeOther='Cat']").InnerText);