SO_PreserveReferencesHandling_E

using Newtonsoft.Json;
using System;
using System.Collections.Concurrent;
using System.IO;
using System.Xml.Serialization;

namespace Contracts.Helpers
{
    public static class SerialisationHelper
    {
        #region Member Variables

        private readonly static ConcurrentDictionary<Type, XmlSerializer> _xmlSerialiser;
        private readonly static JsonSerializerSettings _jsonSettings;

        #endregion

        #region Constructors

        /// <summary>
        /// Initialises the static instance of the <see cref="SerialisationHelper"/> class.
        /// </summary>
        static SerialisationHelper()
        {
            _xmlSerialiser = new ConcurrentDictionary<Type, XmlSerializer>();
            _jsonSettings = new JsonSerializerSettings()
            {
                TypeNameHandling = TypeNameHandling.Auto,
                ConstructorHandling = ConstructorHandling.AllowNonPublicDefaultConstructor,
                PreserveReferencesHandling = PreserveReferencesHandling.Objects,
                ObjectCreationHandling = ObjectCreationHandling.Auto
            };
        }

        #endregion

        #region Methods

        /// <summary>
        /// Serialises an object.
        /// </summary>
        /// <param name="objectToSerialise">Object to serialise.</param>
        /// <param name="serialiseAsJson">True if to serialise as JSON, otherwise will serialise as XML.</param>
        /// <returns></returns>
        public static string Serialise(object objectToSerialise, bool serialiseAsJson = true)
        {
            string result = null;
            if (serialiseAsJson)
            {
                result = JsonConvert.SerializeObject(objectToSerialise, Formatting.Indented, _jsonSettings);
            }
            else
            {
                using (var writer = new StringWriter())
                {
                    XmlSerializer serialiser = GetXmlSerialiser(objectToSerialise.GetType());
                    serialiser.Serialize(writer, objectToSerialise);
                    result = writer.ToString();
                }
            }

            return result;
        }

        /// <summary>
        /// Deserialises an object.
        /// </summary>
        /// <param name="serialisedObject">Object to deserialise</param>
        /// <param name="deserialiseFromJson">True if to deserialise from JSON, otherwise will deserialise from XML.</param>
        /// <returns></returns>
        public static TResult Deserialise<TResult>(string serialisedObject, bool deserialiseFromJson = true) where TResult : class
        {
            TResult result = null;
            if (deserialiseFromJson)
            {
                try
                {
                    result = JsonConvert.DeserializeObject<TResult>(serialisedObject, _jsonSettings);
                }
                catch(JsonSerializationException)
                {
                    result = null;
                }
                catch (JsonReaderException)
                {
                    result = null;
                }
            }
            else
            {
                XmlSerializer serialiser = GetXmlSerialiser(typeof(TResult));
                using (var reader = new StringReader(serialisedObject))
                {
                    try
                    {
                        result = serialiser.Deserialize(reader) as TResult;
                    }
                    catch (InvalidOperationException)
                    {
                        result = null;
                    }
                }
            }

            return result;
        }

        /// <summary>
        /// Gets an XML Serialiser instance for handling the given object type.
        /// </summary>
        /// <param name="objectType"></param>
        /// <returns></returns>
        private static XmlSerializer GetXmlSerialiser(Type objectType)
        {
            XmlSerializer result = null;
            _xmlSerialiser.TryGetValue(objectType, out result);
            if (result == null)
            {
                result = _xmlSerialiser.AddOrUpdate(objectType, new XmlSerializer(objectType), (ot, s) => s);
            }

            return result;
        }

        #endregion
    }
}