Simplest way to transform XML to HTML with XSLT in C#?

Question

XSLT newbie question: Please fill in the blank in the C# code fragment below:

public static string TransformXMLToHTML(string inputXml, string xsltString) {
  // insert code here to apply the transform specified by xsltString to inputXml 
  // and return the resultant HTML string.
  // You may assume that the xslt output type is HTML.
}

Thanks!

Answer 1

How about:

public static string TransformXMLToHTML(string inputXml, string xsltString)
{
    XslCompiledTransform transform = new XslCompiledTransform();
    using(XmlReader reader = XmlReader.Create(new StringReader(xsltString))) {
        transform.Load(reader);
    }
    StringWriter results = new StringWriter();
    using(XmlReader reader = XmlReader.Create(new StringReader(inputXml))) {
        transform.Transform(reader, null, results);
    }
    return results.ToString();
}

Note that ideally you would cache and re-use the XslCompiledTransform - or perhaps use XslTransform instead (it is marked as deprecated, though).

Answer 2

Just for fun, a slightly less elegant version that implements the caching suggested by Marc:

    public static string TransformXMLToHTML(string inputXml, string xsltString)
    {
        XslCompiledTransform transform = GetAndCacheTransform(xsltString);
        StringWriter results = new StringWriter();
        using (XmlReader reader = XmlReader.Create(new StringReader(inputXml)))
        {
            transform.Transform(reader, null, results);
        }
        return results.ToString();
    }

    private static Dictionary<String, XslCompiledTransform> cachedTransforms = new Dictionary<string, XslCompiledTransform>();
    private static XslCompiledTransform GetAndCacheTransform(String xslt)
    {
        XslCompiledTransform transform;
        if (!cachedTransforms.TryGetValue(xslt, out transform))
        {
            transform = new XslCompiledTransform();
            using (XmlReader reader = XmlReader.Create(new StringReader(xslt)))
            {
                transform.Load(reader);
            }
            cachedTransforms.Add(xslt, transform);
        }
        return transform;
    }