May 2006 - Posts

XML Serializable Generic Dictionary

XML Serializable Generic Dictionary

For some reason, the generic Dictionary in .net 2.0 is not XML serializable.  The following code snippet is a xml serializable generic dictionary.  The dictionary is serialzable by implementing the IXmlSerializable interface. 

    using System;

    using System.Collections.Generic;

    using System.Text;

    using System.Xml.Serialization;

 

    [XmlRoot("dictionary")]

    public class SerializableDictionary<TKey, TValue>

        : Dictionary<TKey, TValue>, IXmlSerializable

    {

        #region IXmlSerializable Members

        public System.Xml.Schema.XmlSchema GetSchema()

        {

            return null;

        }

 

        public void ReadXml(System.Xml.XmlReader reader)

        {

            XmlSerializer keySerializer = new XmlSerializer(typeof(TKey));

            XmlSerializer valueSerializer = new XmlSerializer(typeof(TValue));

 

            bool wasEmpty = reader.IsEmptyElement;

            reader.Read();

 

            if (wasEmpty)

                return;

 

            while (reader.NodeType != System.Xml.XmlNodeType.EndElement)

            {

                reader.ReadStartElement("item");

 

                reader.ReadStartElement("key");

                TKey key = (TKey)keySerializer.Deserialize(reader);

                reader.ReadEndElement();

 

                reader.ReadStartElement("value");

                TValue value = (TValue)valueSerializer.Deserialize(reader);

                reader.ReadEndElement();

 

                this.Add(key, value);

 

                reader.ReadEndElement();

                reader.MoveToContent();

            }

            reader.ReadEndElement();

        }

 

        public void WriteXml(System.Xml.XmlWriter writer)

        {

            XmlSerializer keySerializer = new XmlSerializer(typeof(TKey));

            XmlSerializer valueSerializer = new XmlSerializer(typeof(TValue));

 

            foreach (TKey key in this.Keys)

            {

                writer.WriteStartElement("item");

 

                writer.WriteStartElement("key");

                keySerializer.Serialize(writer, key);

                writer.WriteEndElement();

 

                writer.WriteStartElement("value");

                TValue value = this[key];

                valueSerializer.Serialize(writer, value);

                writer.WriteEndElement();

 

                writer.WriteEndElement();

            }

        }

        #endregion

    }

Update: Fixed bug Justin pointed out by adding an extra reader.ReadEndElement() and by checking the IsEmptyElement property.

Posted by pwelter34 | 136 comment(s)
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