sera-slackbot/Bot/Library/JsonFileSaver.cs

using System.Text.Json;
using Microsoft.Extensions.Configuration;
using System.IO;

namespace sera_slackbot.Library
{
    public class JsonFileSaver
    {
        private string path;
        public JsonFileSaver(IConfiguration config)
        {
            path = config.GetSection("Persistence").GetValue<string>("Path");
        }

        public void Save(string filename, dynamic data)
        {
            var filePath = path + "/" + filename;
            File.WriteAllText(filePath, JsonSerializer.Serialize(data, new JsonSerializerOptions { WriteIndented = true }));
        }
    }
}