Yesterday I was trying to write some C# code that uses the .NET XML classes to perform an XSLT transform. I was a bit hampered by not knowing C#, but not much. The tricky thing was working through all of the pertinent classes in the .NET framework.

I needed to transform an XML string (sDataXml) with an XSLT string (sXslt) and get the HTML string that results (sHtml). Further, I needed to pass a parameter to the transform. Here's what I ended up with:

XsltArgumentList vArgs = new XsltArgumentList();
vArgs.AddParam("myParamName", "", "myValue");
XPathDocument xml = new XPathDocument(new StringReader(sDataXml));
XmlUrlResolver resolver = new XmlUrlResolver();
XslTransform xsl = new XslTransform();
Type t = typeof(Kubi.UI.IssuePreviewCtrl);
XmlTextReader xslReader = new XmlTextReader(new StringReader(sXslt))
xsl.Load(xslReader, resolver, Assembly.GetCallingAssembly().Evidence);
StringWriter sw = new StringWriter();
xsl.Transform(xml, vArgs, sw, resolver);
string sHtml = sw.ToString();

In retrospect, the result is not as complicated as it seemed when I was in the middle of it. I understand the value of finely-diced APIs that provide many objects, each with a small job to do. The .NET framework has clearly taken this approach. Being able to pass an explicit URL resolver is a very powerful way to use XSLT in a larger system.

But sometimes you'd like some defaults to help you along. For example, the Evidence passed to xsl.Load: wouldn't that make a wonderful default? And when a XmlUrlResolver is required, a new one constructed with no arguments sounds like a good default.