btcpayserver/BTCPayServer/Services/SettingsRepository.cs

using BTCPayServer.Data;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Identity.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore;
using BTCPayServer.Models;
using Microsoft.EntityFrameworkCore.Infrastructure.Internal;
using Newtonsoft.Json;

namespace BTCPayServer.Services
{
	public class SettingsRepository
	{
		private ApplicationDbContextFactory _ContextFactory;
		public SettingsRepository(ApplicationDbContextFactory contextFactory)
		{
			_ContextFactory = contextFactory;
		}

		public async Task<T> GetSettingAsync<T>()
		{
			var name = typeof(T).FullName;
			using(var ctx = _ContextFactory.CreateContext())
			{
				var data = await ctx.Settings.Where(s => s.Id == name).FirstOrDefaultAsync();
				if(data == null)
					return default(T);
				return Deserialize<T>(data.Value);
			}
		}

		public async Task UpdateSetting<T>(T obj)
		{
			var name = obj.GetType().FullName;
			using(var ctx = _ContextFactory.CreateContext())
			{
				var settings = new SettingData();
				settings.Id = name;
				settings.Value = Serialize(obj);
				ctx.Attach(settings);
				ctx.Entry(settings).State = EntityState.Modified;
				try
				{
					await ctx.SaveChangesAsync();
				}
				catch(DbUpdateException)
				{
					ctx.Entry(settings).State = EntityState.Added;
					await ctx.SaveChangesAsync();
				}
			}
		}

		private T Deserialize<T>(string value)
		{
			return JsonConvert.DeserializeObject<T>(value);
		}

		private string Serialize<T>(T obj)
		{
			return JsonConvert.SerializeObject(obj);
		}
	}
}