public UserModel LogIn(string username, string password)
        {
            UserModel model = null;

            var decodedPass = CommonMethods.Base64Decode(password);
            var user        = context.user.Where(u => u.username.CompareTo(username) == 0).FirstOrDefault();

            if (user != null)
            {
                if (String.Compare(user.username, username, false) != 0 || String.Compare(CommonMethods.Base64Decode(user.password), decodedPass) != 0)
                {
                    throw new UserCredentialsException(ExceptionsRes.res_01);
                }

                model           = new UserModel();
                model.Email     = user.email;
                model.FirstName = user.first_name;
                model.LastName  = user.last_name;
                model.UserId    = user.user_id;
                model.Username  = user.username;
            }
            else
            {
                throw new UserCredentialsException(ExceptionsRes.res_01);
            }

            return(model);
        }