DataTableConverter.cs

#region License
// Copyright (c) 2007 James Newton-King
//
// Permission is hereby granted, free of charge, to any person
// obtaining a copy of this software and associated documentation
// files (the "Software"), to deal in the Software without
// restriction, including without limitation the rights to use,
// copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following
// conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.
#endregion

#if !(SILVERLIGHT || NETFX_CORE || PORTABLE40 || PORTABLE)
using System;
using System.Data;
using Newtonsoft.Json.Serialization;

namespace Newtonsoft.Json.Converters
{
    /// <summary>
    /// Converts a <see cref="DataTable"/> to and from JSON.
    /// </summary>
    public class DataTableConverter : JsonConverter
    {
        /// <summary>
        /// Writes the JSON representation of the object.
        /// </summary>
        /// <param name="writer">The <see cref="JsonWriter"/> to write to.</param>
        /// <param name="value">The value.</param>
        /// <param name="serializer">The calling serializer.</param>
        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
        {
            DataTable table = (DataTable)value;
            DefaultContractResolver resolver = serializer.ContractResolver as DefaultContractResolver;

            writer.WriteStartArray();

            foreach (DataRow row in table.Rows)
            {
                writer.WriteStartObject();
                foreach (DataColumn column in row.Table.Columns)
                {
                    if (serializer.NullValueHandling == NullValueHandling.Ignore && (row[column] == null || row[column] == DBNull.Value))
                        continue;

                    writer.WritePropertyName((resolver != null) ? resolver.GetResolvedPropertyName(column.ColumnName) : column.ColumnName);
                    serializer.Serialize(writer, row[column]);
                }
                writer.WriteEndObject();
            }

            writer.WriteEndArray();
        }

        /// <summary>
        /// Reads the JSON representation of the object.
        /// </summary>
        /// <param name="reader">The <see cref="JsonReader"/> to read from.</param>
        /// <param name="objectType">Type of the object.</param>
        /// <param name="existingValue">The existing value of object being read.</param>
        /// <param name="serializer">The calling serializer.</param>
        /// <returns>The object value.</returns>
        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
        {
            DataTable dt = existingValue as DataTable;

            if (dt == null)
            {
                // handle typed datasets
                dt = (objectType == typeof(DataTable))
                    ? new DataTable()
                    : (DataTable)Activator.CreateInstance(objectType);
            }

            if (reader.TokenType == JsonToken.PropertyName)
            {
                dt.TableName = (string)reader.Value;

                reader.Read();
            }

            reader.Read();

            while (reader.TokenType == JsonToken.StartObject)
            {
                DataRow dr = dt.NewRow();
                reader.Read();

                while (reader.TokenType == JsonToken.PropertyName)
                {
                    string columnName = (string)reader.Value;

                    reader.Read();

                    if (!dt.Columns.Contains(columnName))
                    {
                        Type columnType = GetColumnDataType(reader.TokenType);
                        dt.Columns.Add(new DataColumn(columnName, columnType));
                    }

                    dr[columnName] = reader.Value ?? DBNull.Value;
                    reader.Read();
                }

                dr.EndEdit();
                dt.Rows.Add(dr);

                reader.Read();
            }

            return dt;
        }

        private static Type GetColumnDataType(JsonToken tokenType)
        {
            switch (tokenType)
            {
                case JsonToken.Integer:
                    return typeof(long);
                case JsonToken.Float:
                    return typeof(double);
                case JsonToken.String:
                case JsonToken.Null:
                case JsonToken.Undefined:
                    return typeof(string);
                case JsonToken.Boolean:
                    return typeof(bool);
                case JsonToken.Date:
                    return typeof(DateTime);
                default:
                    throw new ArgumentOutOfRangeException();
            }
        }

        /// <summary>
        /// Determines whether this instance can convert the specified value type.
        /// </summary>
        /// <param name="valueType">Type of the value.</param>
        /// <returns>
        /// 	<c>true</c> if this instance can convert the specified value type; otherwise, <c>false</c>.
        /// </returns>
        public override bool CanConvert(Type valueType)
        {
            return typeof(DataTable).IsAssignableFrom(valueType);
        }
    }
}

#endif