Serializing private member data

You could use DataContractSerializer (but note you can't use xml attributes - only xml elements):

using System;using System.Runtime.Serialization;using System.Xml;[DataContract]class MyObject {    public MyObject(Guid id) { this.id = id; }    [DataMember(Name="Id")]    private Guid id;    public Guid Id { get {return id;}}}static class Program {    static void Main() {        var ser = new DataContractSerializer(typeof(MyObject));        var obj = new MyObject(Guid.NewGuid());        using(XmlWriter xw = XmlWriter.Create(Console.Out)) {            ser.WriteObject(xw, obj);        }    }}

Alternatively, you can implement IXmlSerializable and do everything yourself - but this works with XmlSerializer, at least.

You could use the System.Runtime.Serialization.NetDataContractSerializer. It is more powerful and fixes some issues of the classic Xml Serializer.

Note that there are different attributes for this one.

[DataContract]public class X{  [DataMember]  public Guid Id { get; private set; }}NetDataContractSerializer serializer = new NetDataContractSerializer();TextWriter tw = new StreamWriter(_location);serializer.Serialize(tw, obj);

Edit:

Update based on Marc's comment: You should probably use System.Runtime.Serialization.DataContractSerializer for your case to get a clean XML. The rest of the code is the same.

Read only fields will not be serialized using the XmlSerializer, this is due to the nature of the readonly keyword

From MSDN:

The readonly keyword is a modifier that you can use on fields. When a field declaration includes a readonly modifier, assignments to the fields introduced by the declaration can only occur as part of the declaration or in a constructor in the same class.

So... you would pretty much need to set the fields value in the default constructor...