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

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.

Here's a though for you to consider.

You can have a class that is a container class like this:

class ContainerObject
{
     public int MyNewProperty { get; set; }

     [XmlElement("")]
     public List<int> MyList { get; set; }
}

The trick is to have XmlElement name = "" above the List element.

When this is serialized into xml, you will have:

<ContainerObject>
   <MyNewProperty>...</MyNewProperty>

   <int>...</int>
   <int>...</int>

</ContainerObject>

If you like, you can also create another class for items in a list

 class MyItem
 {
     public int MyProperty {get;set;} 

 } 

and then instead of having List of ints, have a List of MyItems.

This was you control XmlElement name of every item in a list.

I hope this was helpful.