using System;

using System.Collections.Generic;

using System.IO;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        var group = new ElementGroup

        {

            Name = "Group 1",

            Elements = new List<Element>

            {

                new Element

                {

                    Name = "Element 1",

                    Coordinates = new List<List<double>>

                    {

                        new List<double> { 1.1, 1.2, 1.3 },

                        new List<double> { 2.1, 2.2, 2.3 },

                        new List<double> { 3.1, 3.2, 3.3 }

                    },

                    Indices = new List<int> { 1, 2, 3, 4, 6, 7, 8, 10 },

                    Volume = 123.4776,

                    Voids = 73.27857,

                    Type = "foo",

                    Guid = "fgdhgt985hfwe",

                    Quality = "abc"

                },

                new Element

                {

                    Name = "Element 2",

                    Coordinates = new List<List<double>>

                    {

                        new List<double> { 4.1, 4.2, 4.3 },

                        new List<double> { 5.1, 5.2, 5.3 },

                        new List<double> { 6.1, 6.2, 6.3 }

                    },

                    Indices = new List<int> { 3, 5, 7, 8, 9, 11, 18, 20 },

                    Volume = 224.9833,

                    Voids = 91.54733,

                    Type = "bar",

                    Guid = "ghtejkh309gjs",

                    Quality = "def"

                },

            }

        };

​

        string json = JsonHelper.SerializeWithCustomIndenting(group);

        Console.WriteLine(json);

    }

}

​

public static class JsonHelper

{

    public static string SerializeWithCustomIndenting(object obj)

    {

        using (StringWriter sw = new StringWriter())

        using (JsonWriter jw = new CustomJsonTextWriter(sw))   // change this to new JsonTextWriter(sw) to see the default formattingg

        {

            jw.Formatting = Formatting.Indented;

            JsonSerializer ser = new JsonSerializer();

            ser.Serialize(jw, obj);

            return sw.ToString();

        }

    }

} 

​

public class CustomJsonTextWriter : JsonTextWriter

{

    public CustomJsonTextWriter(TextWriter writer) : base(writer)

    {

    }

​

    protected override void WriteIndent()

    {

        if (WriteState != WriteState.Array)

            base.WriteIndent();

        else

            WriteIndentSpace();

    }

}

​

public class ElementGroup

{

    public string Name { get; set; }

    public List<Element> Elements { get; set; }

}

​

public class Element

{

    public string Name { get; set; }

    public List<List<double>> Coordinates { get; set; }

    public List<int> Indices { get; set; }

    public double Volume { get; set; }

    public double Voids { get; set; }

    public string Type { get; set; }

    public string Guid { get; set; }

    public string Quality { get; set; }

}

​