hannan-sultan

public void ConfigureServices(IServiceCollection services)
{
    services.AddControllers()
        .AddJsonOptions(
    options =>
    {
        options.JsonSerializerOptions.PropertyNamingPolicy =
            SnakeCaseNamingPolicy.Instance;
    }); ;
}

hannan-sultan

public static class StringUtils
{
    public static string ToSnakeCase(this string str)
    {
        return string.Concat(str.Select((x, i) => i > 0 && char.IsUpper(x) ? "_" + x.ToString() : x.ToString())).ToLower();
    }
}

hannan-sultan

public class SnakeCaseNamingPolicy : JsonNamingPolicy
{
    public static SnakeCaseNamingPolicy Instance { get; } = new SnakeCaseNamingPolicy();

    public override string ConvertName(string name)
    {
        // Conversion to other naming conventaion goes here. Like SnakeCase, KebabCase etc.
        return name.ToSnakeCase();
    }
}