List of List of struct not serializing. System.RuntimeType is inaccessible due to its protection level. Only public types can be processed

Question

I am trying to serialize an object in XML so that I will be able to deserialize it in silverlight. Pasted below is the code.

StringBuilder builder = new StringBuilder();
var serializer = new XmlSerializer(data.GetType());
var writer = XmlWriter.Create(builder);
serializer.Serialize(writer, data); //error here
string xml = builder.ToString();

The code is throwing this error for data

"System.RuntimeType is inaccessible due to its protection level. Only public types can be processed."

The object data is actually

 List<List<LabelValueTypeGroup>>

where LabelValueType is declared as

[Serializable]
[XmlRoot]
public struct LabelValueTypeGroup/* : IEnumerable*/
{
    public string Label { get; set; }
    public Type Type { get; set; }
    public string Value { get; set; }
    public ComparisonType? ComparisonType { get; set; }

    public IEnumerator GetEnumerator()
    {
        yield return this.Label;
        yield return this.Type;
        yield return this.Value;
        yield return this.ComparisonType;
    }
}

What am I doing wrong? Is List not serialize-able or what? Why I am doing it this way is because, I want to pass an object from WCF to Silverlight that is resulting from a select query, that would only select the columns found in an xml file. So I have to create a sort of dynamic serialize-able object which could be de-serialized in Silverlight. Javascriptserializer and JSON are not accessible in Silverlight project.

Answer 1

It's probably the public Type Type { get; set; } field, holding a reference to a RuntimeType instance which causes the error. RuntimeType is not serializable, that is what the error message tells you.