using System;

using System.Collections.Generic;

using System.Linq;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

public class Program

{

    public static void Main()

    {

        string json = @"

        [

            {

            ""id"": 0,

            ""label"": ""user"",

            ""FirstName"": [ ""Azhar"" ],

            ""LastName"": [ ""Rahi"" ]

            },

            {

            ""id"": 3,

            ""label"": ""user"",

            ""FirstName"": [ ""John"" ],

            ""LastName"": [ ""Doe"" ]

            }

        ]";

​

        List<User> users = JsonConvert.DeserializeObject<List<User>>(json);

        foreach (User user in users)

        {

            Console.WriteLine($"{user.Label} {user.Id}: {user.FirstName} {user.LastName}");

        }

    }

}

​

public class User

{

    public int Id { get; set; }

    public string Label { get; set; }

    [JsonConverter(typeof(ArrayToSingleStringConverter))]

    public string FirstName { get; set; }

    [JsonConverter(typeof(ArrayToSingleStringConverter))]

    public string LastName { get; set; }

}

​

public class ArrayToSingleStringConverter : JsonConverter

{

    public override bool CanConvert(Type objectType)

    {

        return objectType == typeof(string);

    }

​

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)

    {

        JToken token = JToken.Load(reader);

        switch (token.Type)

        {

            case JTokenType.Array:

                return (string)token.Children<JValue>().FirstOrDefault();

            case JTokenType.String:

                return (string)token;

            case JTokenType.Null:

                return null;

            default:

                throw new JsonException("Unexpected token type: " + token.Type);

        }

    }

​

    public override bool CanWrite => false;

​

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)

    {

        throw new NotImplementedException();

    }

}

​