using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Diagnostics;

using System.IO;

using System.Threading;

using System.Collections.ObjectModel;

using System.Globalization;

using System.Net;

​

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;

​

// https://stackoverflow.com/questions/44839515/how-to-convert-ienumerablejtoken-to-jarray/44839613#44839613

    class TestClass

    {

        public static void Test()

        {

            var arrPupilEmailDetails = JArray.Parse(GetJson());         

​

            var gidClassId = "1";

            var query = arrPupilEmailDetails.Where(joSameClass => joSameClass["uClassId"].ToString() == gidClassId.ToString());

            var arrSameClass = new JArray(query);           

            Console.WriteLine(arrSameClass);

        }

        static string GetJson()

        {

            var json = @"[{

    ""name"":""jon bones"",

    ""uClassId"": ""1"",

    ""groups"":[{

        ""groupName"":""Region"",

        ""code"":""1""

    },{

        ""groupName"":""Class"",

        ""code"":""4""

    }]

},

{

    ""name"":""Swan moans"",

    ""uClassId"": ""2"",

    ""groups"":[{

        ""groupName"":""Region"",

        ""code"":""12""

    },{

        ""groupName"":""Class"",

        ""code"":""1""

    }]

}]";

            return json;

        }

    }

​

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Environment version: " + Environment.Version);

            Console.WriteLine("Json.NET version: " + typeof(JsonSerializer).Assembly.FullName);

            Console.WriteLine("");

            TestClass.Test();

        }

    }