XML Canonicalization returns empty elements in the transformed output

Question

I have a related post asking how to select nodes from an XmlDocument using an XPath statement.

The only way I could get the SelectNodes to work was to create a non default namespace "x" and then explicitly reference the nodes in the XPath statement.

Whilst this works and provides me with a node list, the canonicalization then fails to produce any content to my selected nodes in the output.

I've tried using XmlDsigExcC14NTransform and specifying the namespace but this produces the same output.

Below is an example of the xml output produced (using the XML in my related post):

<Applications xmlns="http://www.myApps.co.uk/">
  <Application>
    <ApplicantDetails>
      <Title>
      </Title>
      <Forename>
      </Forename>
      <Middlenames>
        <Middlename>
        </Middlename>
      </Middlenames>
      <PresentSurname>
      </PresentSurname>
      <CurrentAddress>
        <Address>
          <AddressLine1>
          </AddressLine1>
          <AddressLine2>
          </AddressLine2>
          <AddressTown>
          </AddressTown>
          <AddressCounty>
          </AddressCounty>
          <Postcode>
          </Postcode>
          <CountryCode>
          </CountryCode>
        </Address>
        <ResidentFromGyearMonth>
        </ResidentFromGyearMonth>
      </CurrentAddress>
    </ApplicantDetails>
  </Application>
  <Application>
    <ApplicantDetails>
      <Title>
      </Title>
      <Forename>
      </Forename>
      <Middlenames>
        <Middlename>
        </Middlename>
      </Middlenames>
      <PresentSurname>
      </PresentSurname>
      <CurrentAddress>
        <Address>
          <AddressLine1>
          </AddressLine1>
          <AddressLine2>
          </AddressLine2>
          <AddressTown>
          </AddressTown>
          <AddressCounty>
          </AddressCounty>
          <Postcode>
          </Postcode>
          <CountryCode>
          </CountryCode>
        </Address>
        <ResidentFromGyearMonth>
        </ResidentFromGyearMonth>
      </CurrentAddress>
    </ApplicantDetails>
  </Application>
</Applications>

Answer 1

Another StackOverflow user has had a similar problem here

Playing around with this new code, I found that the results differ depending upon how you pass the nodes into the LoadInput method. Implementing the code below worked.

I'm still curious as to why it works one way and not another but will leave that for a rainy day

static void Main(string[] args)
{
    string path = @"..\..\TestFiles\Test_1.xml";
    if (File.Exists(path) == true)
    {
        XmlDocument xDoc = new XmlDocument();
        xDoc.PreserveWhitespace = true;
        using (FileStream fs = new FileStream(path, FileMode.Open))
        {
            xDoc.Load(fs);
        }

        //Instantiate an XmlNamespaceManager object. 
        System.Xml.XmlNamespaceManager xmlnsManager = new System.Xml.XmlNamespaceManager(xDoc.NameTable);

        //Add the namespaces used to the XmlNamespaceManager.
        xmlnsManager.AddNamespace("x", "http://www.myApps.co.uk/");

        // Create a list of nodes to have the Canonical treatment
        XmlNodeList nodeList = xDoc.SelectNodes("/x:ApplicationsBatch/x:Applications|/x:ApplicationsBatch/x:Applications//*", xmlnsManager);

        //Initialise the stream to read the node list
        MemoryStream nodeStream = new MemoryStream();
        XmlWriter xw = XmlWriter.Create(nodeStream);
        nodeList[0].WriteTo(xw);
        xw.Flush();
        nodeStream.Position = 0;

        // Perform the C14N transform on the nodes in the stream
        XmlDsigC14NTransform transform = new XmlDsigC14NTransform();
        transform.LoadInput(nodeStream);

        // use a new memory stream for output of the transformed xml 
        // this could be done numerous ways if you don't wish to use a memory stream
        MemoryStream outputStream = (MemoryStream)transform.GetOutput(typeof(Stream));
        File.WriteAllBytes(@"..\..\TestFiles\CleanTest_1.xml", outputStream.ToArray());
    }
}