using System;

using System.Text.RegularExpressions;

using Newtonsoft.Json;

using Newtonsoft.Json.Serialization;

​

public class Program

{

    public static void Main()

    {

        string json = @"{

                ""part_1"": ""part_1"",

                ""part_2"": ""part_2"",

                ""part_3"": ""part_3"",

                ""totalNum"": 1,

                ""ab_cd_ef"": ""ab_cd_ef""

            }";

        DefaultContractResolver contractResolver = new DefaultContractResolver

        {

            NamingStrategy = new SnakeCaseWithNumberNamingStrategy(),

​

        };

        Welcome4 model = JsonConvert.DeserializeObject<Welcome4>(json, new JsonSerializerSettings { ContractResolver = contractResolver });

        Console.WriteLine(model.Part1);

        Console.WriteLine(model.Part2);

        Console.WriteLine(model.Part3);

    }

}

​

public partial class Welcome4

{

    public string Part1 { get; set; }

    public string Part2 { get; set; }

    public string Part3 { get; set; }

    public int TotalNum { get; set; }

    public string AbCdEf{ get; set; }

}

​

public class SnakeCaseWithNumberNamingStrategy : SnakeCaseNamingStrategy

{

    private readonly Regex regex = new Regex(@"(?<=[A-Za-z])(?=\d)|(?<=\d)(?=[A-Za-z])");

    private readonly char separator = '_';

    public SnakeCaseWithNumberNamingStrategy(bool processDictionaryKeys, bool overrideSpecifiedNames)

        : base(processDictionaryKeys, overrideSpecifiedNames)

    {

        ProcessDictionaryKeys = processDictionaryKeys;

        OverrideSpecifiedNames = overrideSpecifiedNames;

    }

​

    public SnakeCaseWithNumberNamingStrategy(bool processDictionaryKeys, bool overrideSpecifiedNames, bool processExtensionDataNames) : this(processDictionaryKeys, overrideSpecifiedNames)

    {

        ProcessExtensionDataNames = processExtensionDataNames;

    }

​

    public SnakeCaseWithNumberNamingStrategy()

    {

    }

​

    protected override string ResolvePropertyName(string name)

    {

        return ResolvePropertyNameWithNumber(base.ResolvePropertyName(name));

    }

    private string ResolvePropertyNameWithNumber(string name)

    {        

        string formattedName = regex.Replace(name, separator.ToString());

        return formattedName;

    }

}