How to write a comment to an XML file when using the XmlSerializer?

Question

I have an object Foo which I serialize to an XML stream.

public class Foo {
  // The application version, NOT the file version!
  public string Version {get         


        

Answer 1

Isn't possible using default infrastructure. You need to implement IXmlSerializable for your purposes.

Very simple implementation:

public class Foo : IXmlSerializable
{
    [XmlComment(Value = "The application version, NOT the file version!")]
    public string Version { get; set; }
    public string Name { get; set; }


    public void WriteXml(XmlWriter writer)
    {
        var properties = GetType().GetProperties();

        foreach (var propertyInfo in properties)
        {
            if (propertyInfo.IsDefined(typeof(XmlCommentAttribute), false))
            {
                writer.WriteComment(
                    propertyInfo.GetCustomAttributes(typeof(XmlCommentAttribute), false)
                        .Cast().Single().Value);
            }

            writer.WriteElementString(propertyInfo.Name, propertyInfo.GetValue(this, null).ToString());
        }
    }
    public XmlSchema GetSchema()
    {
        throw new NotImplementedException();
    }

    public void ReadXml(XmlReader reader)
    {
        throw new NotImplementedException();
    }
}

[AttributeUsage(AttributeTargets.Property, AllowMultiple = false)]
public class XmlCommentAttribute : Attribute
{
    public string Value { get; set; }
}

Output:

  
  1.2
  A

Another way, maybe preferable: serialize with default serializer, then perform post-processing, i.e. update XML, e.g. using XDocument or XmlDocument.