C# XPath id() not working?

Question

I'm using C# and I'm stumped. Does it just not support id()? I have a large XML file, about 4-5 of them at ~400kb, so I need some speed and performance wherever I can get it.

I use XmlDocument.SelectSingleNode("id('blahblahblah')") and it doesn't get the node by id. Am I going crazy or is it that C# XPath just doesn't support id()?

Answer 1

Use XmlDocument.GetElementById to get the XmlElement with the specified ID, e.g.:

XmlElement elem = doc.GetElementById("blahblahblah");

This works only with documents specifying a DTD though:

Attributes with the name "ID" are not of type ID unless so defined in the DTD.

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In case your document does not have a DTD, you could use an XPath expression to select the node with the id attribute set to your ID:

XmlElement elem = doc.SelectSingleNode("//*[@id='blahblahblah']");