mycorerepository/MyCore/Services/MyControlPanel/UserService.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace MyCore.Services.MyControlPanel
{
    public class UserService
    {
        private static UserDatabaseService _UserDatabaseService;

        public static bool IsExist(string userId)
        {
            return _UserDatabaseService.GetById(userId) != null ? true : false ;
        }

    }
}