When a class is inherited from List<>, XmlSerializer doesn't serialize other attributes

Question

I'm having a situation here, I need my class to be inherited from List<ItemType>, but when I do this XmlSerializer does not serialize any property or field declared in my class, the following sample demonstrates:

public partial class Form1 : Form {     public Form1()     {         InitializeComponent();         DoSerialize();     }     private void DoSerialize()     {         MyClass obj = new MyClass();         obj.Add(1);         obj.Add(2);         obj.Add(3);         XmlSerializer s = new XmlSerializer(typeof(MyClass));         StringWriter sw = new StringWriter();         s.Serialize(sw, obj);     } } [Serializable] [XmlRoot] public class MyClass : List<int> {     public MyClass()     {     }     int myAttribute = 2011;     [XmlAttribute]     public int MyAttribute     {         get         {             return myAttribute;         }         set         {             myAttribute = value;         }     } } 

the resulting XML:

<?xml version="1.0" encoding="utf-16"?> <ArrayOfInt xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">   <int>1</int>   <int>2</int>   <int>3</int> </ArrayOfInt> 

Answer 1

This is by design. I don't know why this decision was made, but it is stated in the documentation:

• Classes that implement ICollection or IEnumerable. Only collections are serialized, not public properties.

(Look under "Items that can be serialized" section). Someone has filed a bug against this, but it won't be changed - here, Microsoft also confirms that not including the properties for classes implementing ICollection is in fact the behaviour of XmlSerializer.

A workaround would be to either:

• Implement IXmlSerializable and control serialization yourself.

or

• Change MyClass so it has a public property of type List (and don't subclass it).

or

• Use DataContractSerializer, which handles this scenario.