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 Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;    

​

// https://stackoverflow.com/questions/49065012/how-to-use-a-string-value-in-run-time-in-selecttoken-jsonpath-query#49065012

​

    class TestClass

    {

        public static void Test()

        {

            var json = GetJson();

            JObject rootJObject = JObject.Parse(json);

            string studentName = "student 1";

            var result = rootJObject.SelectToken(string.Format("$.students[?(@.name=='{0}')]", studentName));

            Console.WriteLine(result);

            Assert.IsTrue((string)result["name"] == studentName);

            var result2 = rootJObject.SelectToken("$.students[?(@.name=='" + studentName + "')]");

​

            Console.WriteLine(result2);

            Assert.IsTrue((string)result2["name"] == studentName);

        }

        static string GetJson()

        {

            var json = @"{

  ""students"": [

    {

      ""name"": ""student 1"",

      ""grades"": [

        {

          ""subject1"": ""A"",

          ""subject2"": ""B""

        }

      ]

    }

  ]

}";

            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();

​

            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

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

                Console.WriteLine(ex);

                throw;

            }

        }

    }

​

    public class AssertionFailedException : System.Exception

    {

        public AssertionFailedException() : base() { }

​

        public AssertionFailedException(string s) : base(s) { }

    }

​

    public static class Assert

    {

        public static void IsTrue(bool value)

        {

            IsTrue(value, "failed");

        }

​

        public static void IsTrue(bool value, string message)

        {

            if (value == false)

                throw new AssertionFailedException(message ?? "failed");

        }

    }

​