How to chain/nest XSL Transforms in .NET

Question

Context: .NET Framework 3.5

I realize how I can perform a single XML transformation using XSLT, but didn't find any good examples on chaining XML transformations.

Input: - XML document as XPathDocument. - File paths to multiple XSL files.

Expected output: - preferably XPathDocument/IXPathNavigable, representing the XML with all transformations applied, one by one.

Example scenario:

input xml: <doc></doc>

xsl-1: .xsl that adds <one /> as a child of the doc element. xsl-2: .xsl that adds <two /> as a child of the doc element.

Expected result

<doc><one /><two /></doc>

Goals

Leverage the forward only nature of XPathDocument/IXPathNavigable or better. Avoid loading entire document in memory.

Answer 1

Maybe something like the following (I have not tried to compile this):

XslCompiledTransform xsl1 = new XslCompiledTransform();
xsl1.Load("xsl1.xsl");

XslCompiledTransform xsl2 = new XslCompiledTransform();
xsl1.Load("xsl2.xsl");

using (Stream stream = new MemoryStream())
{
     using (XmlReader xmlReader1 = XmlReader.Create("source.xml"))
     {
          xsl1.Transform(xmlReader1, stream);
     }

     stream1.Position = 0;

     using (XmlReader xmlReader2 = XmlReader.Create(stream))
     {
         xsl2.Transform(xmlReader2, "output.xml");
     }
}

By using the xmlreader you will get the forward only you are looking for. I have just outpu the first result to a MemoryStream but you could do this to a temporary file.

For that extra little bit of performance you may want to look at pre compiling your xslt.

XSLT Compiler (xsltc.exe)