Why isn't there an XML-serializable dictionary

Question

I need an XML-serializable dictionary. Actually, I now have two quite different programs that need one. I was rather surprised to see that .NET doesn't have one. I asked the question elsewhere and got sarcastic responses. I don't understand why it's a stupid question.

Can someone enlighten me, given how dependent various .NET features are on XML serialization, why there isn't an XML-serializable dictionary. Hopefully, you can also explain why some people consider that a daft question. I guess I must be missing something fundamental and I'm hoping you'll be able to fill in the gaps.

Answer 1

They added one in .NET 3.0. If you can, add a reference to System.Runtime.Serialization and look for System.Xml.XmlDictionary, System.Xml.XmlDictionaryReader, and System.Xml.XmlDictionaryWriter.

I would agree that it is not in a particularly discoverable place.

Answer 2

A generic helper to quickly add IXmlSerializable to any (existing) Dictionary without using inheritance:

using System.Xml;
using System.Xml.Serialization;
using System.Collections.Generic;

namespace GameSpace {

    public class XmlSerializerForDictionary {

        public struct Pair<TKey,TValue> {

            public TKey Key;
            public TValue Value;

            public Pair(KeyValuePair<TKey,TValue> pair) {
                Key = pair.Key;
                Value = pair.Value;
            }//method

        }//struct

        public static void WriteXml<TKey,TValue>(XmlWriter writer, IDictionary<TKey,TValue> dict) {

            var list = new List<Pair<TKey,TValue>>(dict.Count);

            foreach (var pair in dict) {
                list.Add(new Pair<TKey,TValue>(pair));
            }//foreach

            var serializer = new XmlSerializer(list.GetType());
            serializer.Serialize(writer, list);

        }//method

        public static void ReadXml<TKey, TValue>(XmlReader reader, IDictionary<TKey, TValue> dict) {

            reader.Read();

            var serializer = new XmlSerializer(typeof(List<Pair<TKey,TValue>>));
            var list = (List<Pair<TKey,TValue>>)serializer.Deserialize(reader);

            foreach (var pair in list) {
                dict.Add(pair.Key, pair.Value);
            }//foreach

            reader.Read();

        }//method

    }//class

}//namespace

And a convenient serializable generic dictionary:

using System.Xml;
using System.Xml.Schema;
using System.Xml.Serialization;
using System.Collections.Generic;

namespace GameSpace {

    public class SerializableDictionary<TKey,TValue> : Dictionary<TKey,TValue>, IXmlSerializable {

        public virtual void WriteXml(XmlWriter writer) {
            XmlSerializerForDictionary.WriteXml(writer, this);
        }//method

        public virtual void ReadXml(XmlReader reader) {
            XmlSerializerForDictionary.ReadXml(reader, this);
        }//method

        public virtual XmlSchema GetSchema() {
            return null;
        }//method

    }//class

}//namespace