XmlDocument in WCF Service method not successfully saving to file using the class' save method

Question

Hello and thanks in advance, I am attempting to take the input from text boxes in a silverlight application and on an event fired by a button click, convert them to an xml string, pass the string and a specified file name to a WCF service call and in that call save the xml to the specifed file(via a string parameter). The code which captures the text into an xml string seems to be successfully working(based on what I see in the variables when debugging) and looks like this:

    private void ServerInfoNext_Click(object sender, RoutedEventArgs e)
                {

                    //new RegisterServerGroupObject instance
                    RegisterServerGroupObject groupInfo= new RegisterServerGroupObject(groupNameTB.Text,1,parentServerNameTB.Text,LeaderNameCB.SelectedItem.ToString());

                    var serializer = new XmlSerializer(typeof(RegisterServerGroupObject));
                    XmlSerializerNamespaces ns = new XmlSerializerNamespaces();
                    ns.Add("","");

                    XmlWriterSettings settings = new XmlWriterSettings();
                    settings.Encoding = Encoding.UTF8;
                    settings.Indent = true;
                    settings.CloseOutput = true;

                    StringBuilder sb = new StringBuilder();

                    using (XmlWriter writer = XmlWriter.Create(sb,settings))
                    {
                        serializer.Serialize(writer, groupInfo);
                        writer.Close();
                    }

                    //sb now contains the xml string with the information from the serialized class
                    string contentsString = sb.ToString();
                    //create instance of XmlWrite service
                    XMLWriteServiceClient xmlClient = new XMLWriteServiceClient();
                    xmlClient.WriteXmlToServerCompleted += new EventHandler<System.ComponentModel.AsyncCompletedEventArgs>(xmlClient_WriteXmlToServerCompleted);
                    xmlClient.WriteXmlToServerAsync("ServerGroups.xml", contentsString);
    }

at this point when the variable contents string is passed to the service method, I can see that it has valid xml, as well as within the service method itself, which looks like this:

public class XMLWriteService : IXMLWriteService
    {
        public void WriteXmlToServer(string filename,string xmlString)
        {
            XmlDocument xDoc = new XmlDocument();
            xDoc.LoadXml(xmlString.ToString());


            try
            {
                xDoc.Save(filename);


            }
            catch (FileNotFoundException e)
            {

                Console.WriteLine(e.InnerException.ToString());
            }
        }
    }

The try/catch block is not indicating that the file("ServerGroups.xml") is not found, and I currently have that xml file in the ClientBin of the server side portion of the project. (the .Web side). However, after the method terminates there is no new xml written to the file. Can someone please tell me what I am doing wrong? I don't know why the XmlDocument class instance is not saving its contents to the file. Thanks in advance!

Answer 1

You aren't passing a path, so it's just going to save the file to the current directory of the WCF service process, whatever that happens to be. Either find out what that is, or do a search on your whole server drive for that file name to see where it's saving it. Better yet, call Path.Combine to append a path to the begining of the file name before you save to it. For instance:

xDoc.Save(Path.Combine("C:\\ClientBin", filename));

To answer your question in the comment below, if you want to append the incoming XML data to the data that is already stored in the XML file on the server, that's a bit more involved. It all depends what the format of the XML is. Since you are using serialization, which by default will only allow one object per XML document (because it puts the object name as the root document element, of which there can only be one), then you would have to have a different XML format. For instance, on the server side, you would need to have some kind of root element on the document under which you could keep appending the incoming RegisterServerGroupObject objects. For instance, if your XML file on the server looked like this:

<?xml version="1.0" encoding="utf-8" ?>
<ListOfRegisterServerGroupObject>
</ListOfRegisterServerGroupObject>

Then, you could append the data by inserting new elements within that root element, like this:

<?xml version="1.0" encoding="utf-8" ?>
<ListOfRegisterServerGroupObject>
    <RegisterServerGroupObject>
        ...
    </RegisterServerGroupObject>
    <RegisterServerGroupObject>
        ...
    </RegisterServerGroupObject>
    ...
</ListOfRegisterServerGroupObject>

To do this, you would need to first load the XML document, then get the root element, then append the incoming XML as a child element. For instance:

public void WriteXmlToServer(string filename, string xmlString)
{
    string filePath = Path.Combine("C:\\ClientBin", filename);
    XmlDocument storage = New XmlDocument();
    storage.Load(filePath); 
    XmlDocument incoming = New XmlDocument();
    incoming.LoadXml(xmlString);
    storage.DocumentElement.AppendChild(incoming.DocumentElement);
    storage.Save(filePath);
}

Answer 2

You may need to 'map' the physical path to the output file within the service

string path = HostingEnvironment.MapPath("~/MyPath/MyFile.xml");