wcf serialization problem

Question

I have a type MyParameter that i pass as a parameter to a wcf service

[Serializable]
public class MyParameter : IXmlSerializable
{
    public string Name { get; set; }
    public string Value { get; set; }
    public string Mytype { get; set; }

    #region IXmlSerializable Members

    public System.Xml.Schema.XmlSchema GetSchema()
    {
        return null;
    }

    public void ReadXml(System.Xml.XmlReader reader)
    {
        XElement e = XElement.Parse(reader.ReadOuterXml());
        IEnumerable<XElement> i = e.Elements();
        List<XElement> l = new List<XElement>(i);
        Name = l[0].Name.ToString();
        Value = l[0].Value.ToString();
        Mytype = l[0].Attribute("type").Value.ToString();
    }

    public void WriteXml(System.Xml.XmlWriter writer)
    {
        writer.WriteStartElement(Name);
        writer.WriteAttributeString("xsi:type", Mytype);
        writer.WriteValue(Value);
        writer.WriteEndElement();
    }

    #endregion
}

The service contract looks like this:

[ServiceContract]
public interface IOperation
{
 [OperationContract]
 void Operation(List<Data> list);
}

Where data defines a data contract

[DataContract]
public class Data
{
 public string Name { get; set; }
 public List<MyParameter> Parameters{ get; set; }
}

When I run the service and test it I get rhe exception in readXml of MyParameter "the prefix xsi is not defined" xsi should define the namespace "http://w3.org/2001/xmlschema-instance"

How do I fix the problem

I am very new to this so a sample code will be very very very helpful thanks

Answer 1

Add:

   writer.WriteAttributeString("xmlns","xsi", null,@"http://w3.org/2001/xmlschema-instance");