using System;

using System.Data;

using System.Linq;

using System.Xml;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

public class Program

{

    public static void Main()

    {

        DataTable myData = new DataTable();

        myData.Columns.Add("ID", typeof(Guid));

        myData.Columns.Add("Name", typeof(string));

        myData.Rows.Add(Guid.NewGuid(), "Name1");

​

        // Reports System.Guid

        Console.WriteLine(myData.Columns["ID"].DataType.FullName);

​

        JsonSerializerSettings settings = new JsonSerializerSettings();

        settings.Converters.Add(new CustomDataTableConverter());

        string mySerializedString = JsonConvert.SerializeObject(myData, settings);

​

        Console.WriteLine(mySerializedString);

​

        myData = JsonConvert.DeserializeObject<DataTable>(mySerializedString, settings);

​

        // Now reports System.Guid as expected

        Console.WriteLine(myData.Columns["ID"].DataType.FullName);  }

}

​

​

class CustomDataTableConverter : JsonConverter

{

    public override bool CanConvert(Type objectType)

    {

        return (objectType == typeof(DataTable));

    }

​

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)

    {

        DataTable dt = (DataTable)value;

        JObject metaDataObj = new JObject();

        foreach (DataColumn col in dt.Columns)

        {

            metaDataObj.Add(col.ColumnName, col.DataType.AssemblyQualifiedName);

        }

        JArray rowsArray = new JArray();

        rowsArray.Add(metaDataObj);

        foreach (DataRow row in dt.Rows)

        {

            JObject rowDataObj = new JObject();

            foreach (DataColumn col in dt.Columns)

            {

                rowDataObj.Add(col.ColumnName, JToken.FromObject(row[col]));

            }

            rowsArray.Add(rowDataObj);

        }

        rowsArray.WriteTo(writer);

    }

​

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)

    {

        JArray rowsArray = JArray.Load(reader);

        JObject metaDataObj = (JObject)rowsArray.First();

        DataTable dt = new DataTable();

        foreach (JProperty prop in metaDataObj.Properties())

        {

            dt.Columns.Add(prop.Name, Type.GetType((string)prop.Value, throwOnError: true));

        }

        foreach (JObject rowDataObj in rowsArray.Skip(1))

        {

            DataRow row = dt.NewRow();

            foreach (DataColumn col in dt.Columns)

            {

                row[col] = rowDataObj[col.ColumnName].ToObject(col.DataType);

            }

            dt.Rows.Add(row);

        }

        return dt;

    }

}