XML Serializable Dictionary


Typically generic dictionaries are not serializable. For serializing the generic dictionaries we can write custom xml serializable dictionary class by inheriting from Dictionary<TKey, TValue> and also implementing the IXmlSerializable interface.

 

Below code snippet contains the code of XMLSerializable dictionary.

 

using System;

using System.Collections.Generic;

using System.Text;

using System.Xml.Serialization;

using System.Runtime.Serialization;

 

namespace CustomType

{

    /// <summary>

    /// Xml serializable dictionary object.

    /// </summary>

    /// <typeparam name="TKey">Key type</typeparam>

    /// <typeparam name="TValue">Object type</typeparam>

    [SerializableAttribute]

    public class XmlSerializableDictionary<TKey, TValue> : Dictionary<TKey, TValue>, IXmlSerializable

    {

        #region Constructors.

        /// <summary>

        /// Initializes a new instance of the <see cref="XmlSerializableDictionary&lt;TKey, TValue&gt;"/> class.

        /// </summary>

        public XmlSerializableDictionary()

            : base()

        {

            // default constructor.

        }

 

        /// <summary>

        /// Initializes a new instance of the <see cref="XmlSerializableDictionary&lt;TKey, TValue&gt;"/> class.

        /// </summary>

        /// <param name="info">A <see cref="T:System.Runtime.Serialization.SerializationInfo"></see> object containing the  

        information required to serialize the <see cref="T:System.Collections.Generic.Dictionary`2"></see>.</param>

        /// <param name="context">A <see cref="T:System.Runtime.Serialization.StreamingContext"></see> structure

        containing the source and destination of the serialized stream associated with the

        <see  cref="T:System.Collections.Generic.Dictionary`2"></see>.</param>

        protected XmlSerializableDictionary(SerializationInfo info, StreamingContext context)

            : base(info, context)

        {

        }

        #endregion

  

        #region Constants.

        private const string ITEM = "item";

        private const string KEY = "key";

        private const string VALUE = "value";

        #endregion

 

 

        #region IXmlSerializable Members

        /// <summary>

        /// This property is reserved, apply the <see cref="T:System.Xml.Serialization.XmlSchemaProviderAttribute"></see> to

        the class instead.

        /// </summary>

        /// <returns>

        /// An <see cref="T:System.Xml.Schema.XmlSchema"></see> that describes the XML representation of the object that is

        produced by the <see cref="M:System.Xml.Serialization.IXmlSerializable.WriteXml(System.Xml.XmlWriter)"></see> method

        and consumed by the <see cref="M:System.Xml.Serialization.IXmlSerializable.ReadXml(System.Xml.XmlReader)"></see>

        method.

        /// </returns>

        public System.Xml.Schema.XmlSchema GetSchema()

        {

            return null;

        }

 

        /// <summary>

        /// Generates an object from its XML representation.

        /// </summary>

        /// <param name="reader">The <see cref="T:System.Xml.XmlReader"></see> stream from which the object is

        deserialized.</param>

        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();

        }

 

        /// <summary>

        /// Converts an object into its XML representation.

        /// </summary>

        /// <param name="writer">The <see cref="T:System.Xml.XmlWriter"></see> stream to which the object is

        serialized.</param>

        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

 

   }

}

 


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