Copy single element of XML document being created by XMLWriter

Question

My C# application has method that takes a list of objects (inputList) as parameter, it creates an XML string using the TextWriter and XMLWriter with the code below and submits to a webservice.

using (TextWriter writer = new Utf8StringWriter())
{
    using (XmlWriter xw = XmlWriter.Create(writer, settings))
    {
        xw.WriteStartElement("submission");
        xw.WriteElementString("version", XMLversion);
        xw.WriteElementString("user", USER_NAME);

        foreach (var obj in inputList)
        {
            xw.WriteStartElement("node");
            xw.WriteElementString("data1", obj.data1.ToString());
            xw.WriteElementString("data2", obj.data2.ToString());
            xw.WriteElementString("data3", obj.data3.ToString());
            xw.WriteElementString("data4", obj.data4.ToString()); 
            xw.WriteEndElement();
        }

    }
    xmlFile = writer.ToString();
}

One of the requirements to to log the submission for each item in the list individual. So I'd like to know if there's a more efficient way to create a string of the XML node within the foreach loop?

I've considered using the XMLReader with the string afterwards but that's a whole new process and while I know I can create it manually, and am happy to do so, I am open to other suggestions. In essence, I'm looking for an efficient technique to generate a string as illustrated below:

<node>
    <data1>obj.data1.ToString()</data1>
    <data2>obj.data2.ToString()</data2>
    <data3>obj.data3.ToString()</data3>
    <data4>obj.data4.ToString()</data4>
</node>

Answer 1

Your XML document does not seem large enough to warrant using XmlWriter and XmlReader. Assuming it can fit comfortably in memory then I'd use XmlDocument, which allows you to get a node's OuterXml (or InnerXml if you prefer) as a string.

var document = new XmlDocument();

var submission = document.CreateElement("submission");
document.AppendChild(submission);

var version = document.CreateElement("version");
submission.AppendChild(version);
var versionText = document.CreateTextNode(XMLversion);
version.AppendChild(versionText);

var user = document.CreateElement("user");
submission.AppendChild(user);
var userText = document.CreateTextNode(USER_NAME);
user.AppendChild(userText);

foreach (var obj in inputList)
{
    var node = document.CreateElement("node");
    submission.AppendChild(node);

    var data1 = document.CreateElement("data1");
    node.AppendChild(data1);
    var data1Text = document.CreateTextNode(obj.data1.ToString());
    data1.AppendChild(data1Text);

    // TODO: repeat last 4 lines for data2, data3 and data4

    Console.WriteLine(node.OuterXml);
}

Console.WriteLine(document.OuterXml);