using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Runtime.Serialization.Formatters;

using System.IO;

using System.Data;

using System.ComponentModel.DataAnnotations;

using System.Globalization;

using System.Reflection;

using System.Collections.ObjectModel;

​

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;    

​

using NUnit.Framework; // Throws NUnit.Framework.AssertionException

​

//https://stackoverflow.com/questions/65512324/how-to-filter-a-json-by-a-string-value-contained-in-an-array-inside-json-using-j

​

    class TestClass

    {

        public static void Test()

        {

            var root = JToken.Parse(GetJson());

            var value = "Maths";

            var subjects = root.SelectTokens($"class.subs[*].subjects[?(@ == '{value}')]");

            Console.WriteLine(JsonConvert.SerializeObject(subjects, Formatting.Indented));

​

            var subs = root.SelectTokens($"class.subs[?(@.subjects[?(@ == '{value}')])]");

​

            //?(@ == 'Maths')

            Console.WriteLine(JsonConvert.SerializeObject(subs, Formatting.Indented));

            Assert.AreEqual(2, subjects.Count());

            Assert.AreEqual(2, subs.Count());

        }   

        static string GetJson()

        {

            return @"{

   ""class"":{

      ""type"":""group"",

      ""identifier"":""MyFavClass"",

      ""subs"":[

         {

            ""type"":""individual"",

            ""identifier"":""Rambo""

         },

         {

            ""type"":""individual"",

            ""identifier"":""Rancho""

         },

         {

            ""type"":""biggroup"",

            ""identifier"":""village"",

            ""subjects"":[

               ""Maths"",

               ""English""

            ]

         },

         {

            ""type"":""biggroup"",

            ""identifier"":""newvillage"",

            ""subjects"":[

               ""Maths""

            ]

         }

      ]

   }

}

";

        }

    }

​

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Environment version: {0} ({1})", System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription , GetNetCoreVersion());

            Console.WriteLine("{0} version: {1}", typeof(JsonSerializer).Assembly.GetName().Name,  typeof(JsonSerializer).Assembly.FullName);

            Console.WriteLine();

​

            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

                Console.WriteLine("Failed with unhandled exception: ");

                Console.WriteLine(ex);

                throw;

            }

        }

        public static string GetNetCoreVersion()

        {

            //https://techblog.dorogin.com/how-to-detect-net-core-version-in-runtime-ecd65ad695be

            //

            var assembly = typeof(System.Runtime.GCSettings).GetTypeInfo().Assembly;

            var assemblyPath = assembly.Location.Split(new[] { '/', '\\' }, StringSplitOptions.RemoveEmptyEntries);

            int netCoreAppIndex = Array.IndexOf(assemblyPath, "Microsoft.NETCore.App");

            if (netCoreAppIndex > 0 && netCoreAppIndex < assemblyPath.Length - 2)

                return assemblyPath[netCoreAppIndex + 1];

            return null;

        }

    }

​