Writing code is fun. At least it is for me. But sometimes it gets irritating. You know, you’re busy on something, you write the code, you know it’s right but it doesn’t work… You keep your focus on that one piece of code you just wrote and it keeps on not working. Sometimes, the reason it doesn’t work is obvious but sometimes, you keep reviewing your code, its surrounding, you debug away several variants of your solution and it keeps on not working …
I just had one of those moments…
And then, bang ! The solution jumps at me and it’s so obvious I almost felt shame 
I was writing the unit tests in preparation for my next article on creating a XPathNavigator implementation. The code basically boils down to this:
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TextReader textReader = new StringReader("<root> </root>"); XmlReaderSettings settings = new XmlReaderSettings(); settings.IgnoreWhitespace = false; XmlReader reader = XmlReader.Create(textReader, settings); XPathDocument doc = new XPathDocument(reader); var nav = doc.CreateNavigator().SelectSingleNode("/root/text()"); var success = nav.MoveToParent(); |
I am testing MoveToParent() from a whitespace node. "/root/text()" is expected to give me an XPathNavigator located on the whitespace node inside the <root> element. And nav just keeps on being null. Since I had been busy writing pairs of xml samples and xpath queries to put my test in each situation I needed to test. I immediately assumed my xpath query was not correct. i just kept on tweaking here, there. nav is null still …
After some time, I decided to not put more effort into it and come back to it later, once I can take the necessary step back. I posted a question on stackoverflow.com and worked on something else.
I was busy on something completely different when it struck me. One of those “Haha” moments. XPathDocument has a constructor that takes a XmlSpace enum value. By default, if you don’t specify it, XPathDocument will simply skip all non-significant whitespace node.
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// skips ignorable whitespaces XPathDocument doc = new XPathDocument(reader); // skips also XPathDocument doc = new XPathDocument(reader, XmlSpace.Default); // keeps non-significant whitespaces XPathDocument doc = new XPathDocument(reader, XmlSpace.Preserve); |
That’s it … annoying.