Create a JSON writer for IDataReader aiming to achieve a mild compression using a format similar to protobuf

DataReaderConverter.cs

using Newtonsoft.Json;
using Newtonsoft.Json.Serialization;
using System;
using System.Collections.Generic;
using System.Data;

namespace NewtonSoft.Json.Converters
{
	public class DataReaderConverter : JsonConverter
	{
		public override bool CanConvert(Type objectType)
		{
			return typeof(IDataReader).IsAssignableFrom(objectType);
		}

		public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
		{
			throw new NotImplementedException();
		}

		public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
		{
			var reader = value as IDataReader;
			if (reader == null)
			{
				writer.WriteNull();
				return;
			}

			DefaultContractResolver r = serializer.ContractResolver as DefaultContractResolver;
			Func<string, string> resolver;
			if (r == null)
			{
				resolver = (string colName) => r.GetResolvedPropertyName(colName);
			}
			else
			{
				resolver = (string colName) => colName;
			}
			writer.WriteStartArray();
			MapTable(writer, reader, serializer, resolver);
			while (reader.NextResult())
			{
				MapTable(writer, reader, serializer, resolver);
			}
			writer.WriteEndArray();

		}

		private class Column
		{
			public readonly Type Type;
			public readonly string Name;
			public readonly string Map;
			public Column(Type type, string name,int ordinal)
			{
				Type = type;
				Name = name;
				Map = "C" + ordinal.ToString();
			}
		}

		private void MapTable(JsonWriter writer, IDataReader reader, JsonSerializer serializer, Func<string, string> resolver)
		{
			writer.WriteStartObject();
			var columns = new List<Column>();
			int fieldCount = reader.FieldCount;
			writer.WritePropertyName("schema");
			writer.WriteStartObject();
			for (var i = 0; i < fieldCount; i++)
			{
				var col = new Column(reader.GetFieldType(i), reader.GetName(i),i);
				columns.Add(col);
				writer.WritePropertyName(col.Map);
				writer.WriteValue(col.Name);
			}
			writer.WriteEndObject();

			writer.WritePropertyName("data");
			writer.WriteStartArray();
			while (reader.Read())
			{
				writer.WriteStartObject();
				for (var i = 0; i < fieldCount; i++)
				{

					var col = columns[i];
					var value = reader.GetValue(i);
					if (serializer.NullValueHandling == NullValueHandling.Ignore && (value == null || value == DBNull.Value))
					{
						continue;
					}
					writer.WritePropertyName(resolver(col.Map));
					serializer.Serialize(writer, value, col.Type);
				}

				writer.WriteEndObject();
			}
			writer.WriteEndArray();
			writer.WriteEndObject();
		}
	}
}