using System;

using System.Collections.Generic;

using System.Linq;

using Newtonsoft.Json.Linq;

public class Program

{

    public static void Main()

    {

        string json = @"

            {

              ""data"": [

                {

                  ""id"": ""1"",

                  ""type"": ""Bus"",

                  ""attributes"": {

                    ""property-two"": ""2020-12-10"",

                    ""property-three"": ""D"",

                    ""property-four"": null,

                    ""property-five"": 5

                  }

                },

                {

                  ""id"": ""2"",

                  ""type"": ""Car"",

                  ""attributes"": {

                    ""property-two"": ""2020-12-10"",

                    ""property-three"": ""D"",

                    ""property-four"": null,

                    ""property-five"": 5

                  }

                }

              ]

            }";

​

        var obj = JObject.Parse(json);

        var csv = obj.SelectTokens("..attributes").Cast<JObject>().ToCsv();

        Console.WriteLine(csv);

    }

}

​

public static class JsonHelper

{

    public static string ToCsv(this IEnumerable<JObject> items, bool includeHeaders = true)

    {

        if (!items.Any()) return string.Empty;

        var rows = new List<string>();

        if (includeHeaders)

        {

            rows.Add(items.First().Properties().Select(p => p.Name).ToCsv());

        }

        rows.AddRange(items.Select(jo => jo.Properties().Select(p => p.Value.Type == JTokenType.Null ? null : p.Value).ToCsv()));

        return string.Join(Environment.NewLine, rows);

    }

​

    public static string ToCsv(this IEnumerable<object> values)

    {

        const string quote = "\"";

        const string doubleQuote = "\"\"";

        return string.Join(",", values.Select(v => v != null ? string.Concat(quote, v.ToString().Replace(quote, doubleQuote), quote) : string.Empty));

    }

}