C# XML serialization of derived classes

Question

Hi I am trying to serialize an array of objects which are derived from a class and I keep hitting the same error using c#. Any help is much appreciated.

obviously th

Answer 1

Solution:

class Program
    {
        static void Main(string[] args)
        {
            Shape[] a = new Shape[2] { new Square(1), new Triangle() };

            FileStream fS = new FileStream("C:\\shape.xml",FileMode.OpenOrCreate);

            //this could be much cleaner
            Type[] t = { a[1].GetType(), a[0].GetType() };


            XmlSerializer xS = new XmlSerializer(a.GetType(),t);
            Console.WriteLine("writing");
            try
            {
                xS.Serialize(fS, a);
            }
            catch (Exception e)
            {
                Console.WriteLine(e.InnerException.ToString());
                Console.ReadKey();
            }
            fS.Close();
            Console.WriteLine("Fin");
        }
    }

namespace XMLInheritTests
{
    [XmlInclude(typeof(Square))]
    [XmlInclude(typeof(Triangle))]
    public abstract class Shape
    {
        public Shape() { }
        public int area;
        public int edges;
    }
}

Thanks; I no doubt will have another problem very soon :S

Answer 2

[XmlInclude(typeof(Square))]
public abstract class Shape {...}

(repeat for all known subtypes)

If the types are only known at runtime, you can supply them to the XmlSerializer constructor, but: then it is important to cache and reuse that serializer instance; otherwise you will haemorrhage dynamically created assemblies. It does this automatically when you use the constructor that just takes a Type, but not for the other overloads.