C# How to perform a live xslt transformation on an in memory object?

Question

I have a function that takes 2 parameters : 1 = XML file, 2 = XSLT file, then performs a transformation and returns the resulting HTML.

Here is the function:

/// <summary>
/// Will apply an XSLT style to any XML file and return the rendered HTML.
/// </summary>
/// <param name="xmlFileName">
/// The file name of the XML document.
/// </param>
/// <param name="xslFileName">
/// The file name of the XSL document.
/// </param>
/// <returns>
/// The rendered HTML.
/// </returns>
public string TransformXml(string xmlFileName, string xslFileName)
{
    var xtr = new XmlTextReader(xmlFileName)
                  {
                      WhitespaceHandling = WhitespaceHandling.None
                  };
    var xd = new XmlDocument();
    xd.Load(xtr);

    var xslt = new System.Xml.Xsl.XslCompiledTransform();
    xslt.Load(xslFileName);
    var stm = new MemoryStream();
    xslt.Transform(xd, null, stm);
    stm.Position = 1;
    var sr = new StreamReader(stm);
    xtr.Close();
    return sr.ReadToEnd();
}

I want to change the function not to accept a file for the XML, but instead just an object. The object is exactly compatible with the xslt, if it was serialized to file. But I don't want to have to serialize it to a file first.

So to recap : keep the xslt coming from a file, but the xml input should an object I pass and would like to generate the xml from without any file system interaction.

Answer 1

Here's a function that will turn an object into a XDocument (you can change it for XmlDocument if you aren't using XDocument yet). Of course this will throw exceptions if the object is not serializeable.

public static XDocument ConvertToXml<T>(this T o)
{
    StringBuilder builder = new StringBuilder();
    StringWriter writer = new StringWriter(builder);
    XmlSerializer serializer = new XmlSerializer(typeof(T));
    serializer.Serialize(writer,o);
    StringReader reader = new StringReader(builder.ToString());
    return XDocument.Load(reader);
}

and here's the one for XmlDocument

public static XmlDocument ConvertToXml<T>(this T o)
{
    StringBuilder builder = new StringBuilder();
    StringWriter writer = new StringWriter(builder);
    XmlSerializer serializer = new XmlSerializer(typeof(T));
    serializer.Serialize(writer,o);
    StringReader reader = new StringReader(builder.ToString());
    XmlDocument doc = new XmlDocument();
    doc.Load(reader);
    return doc;
}

Answer 2

Not tested, but you can use the XPathDocument to take a Stream, and since XPathDocument implements IXPathNavigable, it can be used for transformations:

 public string TransformXml(Stream xmlFile, string xslFileName) 
 { 
      var doc = new XPathDocument(xmlFile);
      var xslt = new System.Xml.Xsl.XslCompiledTransform(); 
      xslt.Load(xslFileName); 
      var stm = new MemoryStream(); 
      xslt.Transform(doc, null, stm); 
      stm.Position = 1; 
      var sr = new StreamReader(stm); 
      return sr.ReadToEnd(); 
  } 

Answer 3

You can serialize the object to a string, load the string into a XmlDocument, and perform the transformation :

public string TransformXml(object data, string xslFileName)
{

    XmlSerializer xs = new XmlSerializer(data.GetType());
    string xmlString;
    using (StringWriter swr = new StringWriter())
    {
        xs.Serialize(swr, data);
        xmlString = swr.ToString();
    }

    var xd = new XmlDocument();
    xd.LoadXml(xmlString);

    var xslt = new System.Xml.Xsl.XslCompiledTransform();
    xslt.Load(xslFileName);
    var stm = new MemoryStream();
    xslt.Transform(xd, null, stm);
    stm.Position = 1;
    var sr = new StreamReader(stm);
    xtr.Close();
    return sr.ReadToEnd();
}

Answer 4

Take a look at this article which describes creating an XPathNavigator that can navigate the properties of an object graph, which is a pretty powerful combination of XPath and XSLT.