How to XML-serialize a dictionary

I have been able to serialize an IEnumerable this way:

[XmlArray("TRANSACTIONS")]
[XmlArrayItem("TRANSACTION", typeof(Record))]
public IEnumerable<BudgetRecord> Records
{
    get 
    {
        foreach(Record br in _budget)
        {
            yield return br;
        }
    }
}

However, I realised that now I need a dictionary containing a collection Dictionary<string, RecordCollection> (RecordCollection implements IEnumerable).

How can I achieve that?

Solution

Take a look at the following blog post

and this one (not in english, but the code is useful)

http://huseyint.com/2007/12/xml-serializable-generic-dictionary-tipi/

Code sample from: http://web.archive.org/web/20100703052446/http://blogs.msdn.com/b/psheill/archive/2005/04/09/406823.aspx

using System.Collections.Generic;
using System.Collections;
using System.IO;
using System.Xml.Serialization;
using System.Xml;
using System;
public static void Serialize(TextWriter writer, IDictionary dictionary)
{
    List<Entry> entries = new List<Entry>(dictionary.Count);
    foreach (object key in dictionary.Keys)
    {
        entries.Add(new Entry(key, dictionary[key]));
    }
    XmlSerializer serializer = new XmlSerializer(typeof(List<Entry>));
    serializer.Serialize(writer, entries);
}
public static void Deserialize(TextReader reader, IDictionary dictionary)
{
    dictionary.Clear();
    XmlSerializer serializer = new XmlSerializer(typeof(List<Entry>));
    List<Entry> list = (List<Entry>)serializer.Deserialize(reader);
    foreach (Entry entry in list)
    {
        dictionary[entry.Key] = entry.Value;
    }
}
public class Entry
{
    public object Key;
    public object Value;
    public Entry()
    {
    }

    public Entry(object key, object value)
    {
        Key = key;
        Value = value;
    }
}

It generates output like the following, when the keys and values are strings.

<?xml version="1.0" encoding="utf-8"?>
<ArrayOfEntry xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Entry>
    <Key xsi:type="xsd:string">MyKey</Key>
    <Value xsi:type="xsd:string">MyValue</Value>  
  </Entry>
  <Entry>    
    <Key xsi:type="xsd:string">MyOtherKey</Key>    
    <Value xsi:type="xsd:string">MyOtherValue</Value>  
  </Entry>
</ArrayOfEntry>