using System;

using System.Text.Json;

using Newtonsoft.Json;

using Newtonsoft.Json.Serialization;

using System.Dynamic;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {           

        //TestSystemTextJson("{\"FirstName\":\"Joanna\", \"Data\":{\"Subject\":\"My Test Subject\"}}");

        //TestSystemTextJson("{\"firstName\":\"Joanna\", \"Data\":{\"subject\":\"My Test Subject\"}}");

        //Console.WriteLine("---");

        TestNewtonsoft("{\"FirstName\":\"Joanna\", \"Data\":{\"Subject\":\"My Test Subject\"}}");

        Console.WriteLine();

        TestNewtonsoft("{\"firstName\":\"Joanna\", \"data\":{\"subject\":\"My Test Subject\"}}");

    }

    private static void TestSystemTextJson(string json)

    {

        var jsonSerializerOptions = new JsonSerializerOptions { PropertyNameCaseInsensitive = true, PropertyNamingPolicy = JsonNamingPolicy.CamelCase };

        var person = System.Text.Json.JsonSerializer.Deserialize<Person>(json, jsonSerializerOptions);

        var serializedPerson = System.Text.Json.JsonSerializer.Serialize(person, jsonSerializerOptions);

        Console.WriteLine(" FirstName: " + person.FirstName);

        Console.WriteLine("      Data: " + person.Data);

        Console.WriteLine("Serialized: " + serializedPerson);

    }

    private static void TestNewtonsoft(string json)

    {

        Console.WriteLine("  Original: " + json);

        var contractResolver = new DefaultContractResolver

        {

            NamingStrategy = new CamelCaseNamingStrategy()

        };

        var person = JsonConvert.DeserializeObject<Person>(json, new JsonSerializerSettings {ContractResolver = contractResolver });

        var serializedPerson = JsonConvert.SerializeObject(person, new JsonSerializerSettings {ContractResolver = contractResolver });

        Console.WriteLine("Serialized: " + serializedPerson);

        Console.WriteLine();

        Console.WriteLine(" FirstName: " + person.FirstName);       

        var x = (IDictionary<string, object>)person.Data;

        if (x.ContainsKey("Subject"))

            Console.WriteLine("   Subject: " + x["Subject"]);

        else

            Console.WriteLine("   subject: " + x["subject"]);

    }

}

​

​

public class Person

    {

        public string FirstName {get;set;}

        //[JsonProperty(NamingStrategyType = typeof(CamelCaseNamingStrategy), NamingStrategyParameters = new object[] { false, true })]

        //[JsonProperty(NamingStrategyType = typeof(DefaultNamingStrategy))]    

        public ExpandoObject Data {get;set;}

    }